It is possible, it just depends on you. I would say train like 4*5 hours a week plus 3 hours one-on
-one with a coach. This is 23 hours, IMO it's enough if you are talented. If not, aim at 30-35 hours per week. The real challenge are the money and the schooling. You're 15 and being a full-time TT player you can't expect a stable income. The best if you can participate in a family business. Also, if you are in school and train to become a pro, you can forget your social life. Your team and clubmates will be your friends and you shouldn't start a serious romantic relationship, unless she's a professional too. It's harsh, but it's possible. On the other hand, if you want to become a semi-professional, someone who gets paid for playing but not as his main income, your job is much easier. Then it really depends on how talented you are, how good the coaches are and how can you manage your time. I am 21 and still want to become a semi-pro and I believe that I can become one.
If you decided that you want to take table tennis seriously, I highly recommend to set goals and start to share vids about you training and playing, as it creates pressure on you and helps maintaining a high standard during training.