How can I get the ball in rugby as a fullback?

I'm on my school's gr.10 rugby team and we're first in the region. We have about 4 benchwarmers and the rest are really good, but the only problem is that I hate playing because I'm fullback, and got the ball 2 times in a tournament of 3 games today and no tackles. I'm not bad, it's just that no one every broke through and the other teams dont kick far. I asked my coach to switch my position but he said I'm really good at it and blew me off. If I was really bad then he would have put someone else in, but I played that position all game every game. Any way I can get the ball more? because I'm just going to quit.