After seeing you twice I can say you like to play a pro-style attacking game, but your tools are not yet developed enough to play that way. Still yet, you correctly want to attack first and that is important if you can make that chance for yourself.
I have covered some, but repeat those for effect. Some are new topics.
Slow down. You try to play too fast and are not yet ready for that, but keep up that mentality fro the future when your skills allow you to play faster.
Play quicker. What??? Didn't I just advise to slow down and now I am saying to be quicker? Yes. I am. Indeed. when you decide not to attack, you need to move to the ball and impact it right away. You need to make your decisions earlier, but do it calmly, almost sub-consciously. If the ball does not look right or your confidence is not there, there is nothing wrong with stepping in and giving the ball back. The intent is not just to bump it back and make life easy, but to get back a ball you can manage and attack with more confidence and higher percentage. Sometimes, you have to trust your attack and let go with your shot whether it goes in or not, because not every shot everyone tries lands. However, if it is not there why play high risk? decide early, step in, impact the ball right away off the bounce and place it either short, or to the three GOOD zones (WIDE FH/BH or middle playing elbow). You will very likely see your opponent attempt a very low percentage shot which you have a very good chance to block for a point, you will see opponent miss the shot, or you will see opponent surprised and decide to make an emergency underspin return. You are ready to attack for spin, power, placement or all the above to win the point or setup the finish. sometimes you are away from the table and simply do not want to make a powerloop as it will be lower percentage. You decide early what you want to do and give back a light topspin very low. It goes low over net, lands, kicks, troubles opponent, and opponent gives you back a much easier ball to resume the attack.
Stay on balance and use a shorter backswing. What, give up power? Well, if the ball is there for a sure finish, why not use full power? if it can come back, it will and you need to be ready to continue attacking. Once you learn how to use your legs and hips to start the power, this will become easier if you follow anne's advice and stay low bending your knees some. this helps the lateral movement as well. Often with us amature players who have a career or are full time students busy in life, we do not have the fitness of energy for this. Try best you can. Try to make it a habit over time and it will reward you.
On easy finishing shots, do NOT make a huge backswing. This is a huge mistake amature players make. instead, keep your racket at ball high, step forward, and hit through the ball using the arm swing along with body momentum. The forward momentum gives you the power to use just your arm and still make a powerful shot that will be a winner. it is about control here and a huge backswing wrecks the balance and timing. You will see this time and time again in club play in Korea. Sometimes, I deliberately pop up a ball to see if opponent can move to it and hit with control. Often, I get a free point and am the one snickering as we add a point to our score.
Start BH shot from your chest and keep racket up at start of stroke vs knuckle or topspin. using a bad swing plane will get you in trouble. keep tip of racket up for a control ball that Koreans call SHOT. Tilt the tip to your left to use more wrist to add spin. cock the wrist for even more spin when your timing is better. Start stroke at chest. be in position. it is difficult to land the BH when out of position. Move forward and adjust with bat angle. Remember if you have a fast ball coming to your BH and you need to counter it, stay low, take a step with your left foot if ball is to your wide BH and move side/forward, then keep tip up and hit through ball going forward. You will often land a winner. The BH is a very quick shot makes it difficult to determine direction. You do not need much of a backswing as you start from your chest vs topspin or knuckle. You lost a lot of point by not using the BH as at least a stable, steady shot to get chances to use your FH. Often the point was over when you tried to use your BH, or you decide for a higher risk step around FH. keep your options open and play slowly, but quickly on BH.
Practice serving. I cannot say this strongly enough for you. You have the service motion, but not enough variety of depths, breaks and placements with the same motion. When you can change your serves some more, you will be a TON more effective. You will also be able to read serves a little better if you know how to serve effectively.
Practice pushing underspin both short and long with your partner. you both need to learn to take the ball early and use a loose wrist for short control or to add spin to make it go fast and long. yes, practicing a strong topspin attack is nice, but at the amature levels in Korea, you will win more points by being able to control the ball on shots you decide not to attack. it is all about controlling opponents' options and rushing them into a mistake or causing them to give you a more favorable ball. When we played doubles, I was able to set you up for some really easy finishes when I returned serve. usually, the advantage is the server's advantage. In Korea amature level, if you can make a good underspin, either short, or very sudden/deep, the opponent will time and time again give you a much easier ball to work with. That is why you got those nice chances to attack. I knew all the LP lady would do if I pushed fast and deep zero or light spin to her LP was that she would bump it back. since the ball was fast and deep, it was very difficult for her to return short, so she gave you many predictable knuckle balls long to open your attack, which you were very ready, and made a strong topspin that 99% of time won the point. That is one of the ways to make the middle game work for you. If you are able to return the underspin serve short, what will the J-Pen attacking lady do? She has no choice but to attack it for a lost point, or give the ball back to you, often long, so you can attack. That is the power of good touch and control on your non-attacking shots. they win points or set them up. The more you use this to your advantage, the more weapons you have to win. When you get better, you will need every one of them!
Reading spin. That brings up the point with reading spin. That is a skill that improves as you increase in level, but why not practice it and increase your level? One effective way to read spin is to practice pushing back and forth and have partner randomly change the amount of spin form zero to heavy. You or partner practice stepping to ball and taking it early with loose wrist to return short or long/fast/deep. Any error you make will show, especially on the short returns. You misread the spin and you will net the ball or pop it up next to net, an easy point for opponent and instant feedback if you properly read the spin. that is why it is so important not to just play matches at the club, but find something, even if it is easy to work on.
That is enough for now, but we'll keep talking Brice and maybe you can come up to Uijeongbu soon to my local club.
Maybe we talk about equipment next.