How good do you wanna get at playing the piano? by: David from www.piano-play-it.com
I undertstand your conflict Andrew. I experience this problem with lots of my students who are at about your age.
My answer to you is, How good do you wanna get? Two times a week is enough time to maintain your level and relax from the pressure at school. Chill and have fun.
If you're playing the piano purely for plessure I think it's perfect at the moment. You can maybe also decide with your teacher that you're going to take it slowly in the coming time and improvise or just have fun for some time until your pressure is off.
However, if you're ambitious and you're eagering to improve your technique and playing level, two times a week isn't enough since playing everyday (or let's say atlist five times a week) is important to a good practice. Any practice I believe.
So, basically it's up to you. My bottom line is that you shouldn't feel pressured. Playing the piano should always be fun unless you're going to make your work out of it or become a professional. then pressure is sometimes part of the job I'm afraid.