Conflicted feelings

I've been dating this guy for a few months and my feelings don't make sense to me. I've never liked someone on this level before. I think about him all the time and constantly worry if I am going to screw up or something. I feel like I'm being crazy and obsessive and I don't know what's wrong with me because until now, I've always been the opposite of this. I've never been with someone this nice before and even though I know it's good and I really like it, I'm kind of uncomfortable because of how I'm acting. I don't know what's wrong with me