KayserRF, this is normal. You're not the only one that feels this way. I wanted to quit so many times as a junior. Tennis hadn't really been 'fun' since I was 12. It's tough watching your classmates live the easy life, having fun, going to parties, meeting girls. You start to resent this lifestyle you have and wish you could just be 'normal' like the other kids. You start to think what's the point of it all???
My advice to you is to manage your schedule better. Yes, you should be playing and training year round, but there's no sense in playing 5-6 times a week during the lightest part of the season (e.g. winter) when you don't have many tournaments scheduled, or during the busy part of your calendar when you're playing tournaments back-to-back weekends. You need an off-season. Play another sport in the winter just for fun like basketball or indoor soccer and only pick up your rackets once or twice a week. Cross-training keeps you in shape, works out different muscles, and varying your workouts keeps it interesting. During the middle of the summer you need to let your body rest/recover in between tournaments. Don't work yourself to exhaustion a day or two before a tournament. In the days before/after a tournament I used to get in a short hitting session just to make sure everything is still working and keep the groove, then maybe do a light run to stay loose and stretch.