Matches Only

I am not a very good player but, I am very enthusiastic about table tennis. Nearly 90% of the table tennis I play is at school where, because there are many other people waiting for their turn, I start playing matches without a lot of practice. I am worried that playing matches all the time is not helping my game. I think playing fore-hand counters for about 30 minutes would be far better than playing matches all day. Am I right in assuming that? Also, my backhand is very weak. Extremely weak. Until about a few months ago, I didn't even play with the backhand. I would turn my hand and play the backhand shot with my forehand. So, how do I improve my backhand? Eagerly waiting to hear from you, respected coach.