I can't stop thinking about my girlfriend?

I really love her but it seems to be having a negative effect on me. When I was single I had more fun just hangin with friends and I was also more serious about my passion which is basketball. Ever since my girlfriend came into my life, I just can't stop thinking about her. I feel like all I want to do is be with her. When I get home I feel empty because I know I won't be able to see her until tomorrow at school. I am also on my high school basketball team which is the only thing that makes me somewhat happy. What should I do? I truly want to be with her but It feels like being single I am more happy and motivated.