This just feels wrong?

I've been with my boyfriend for a week and I've been back and forth between liking him, and not. That sounds bad, I know. But I don't know why I feel that way! He is a nice guy, and not bad looking, but sometimes I feel like I shouldn't have gotten with him. Something seems off about him. It almost makes me feel... uncomfortable. When we don't get the chance to talk, I want to. But when we do talk, I question myself why I'm with him in the first place. I don't know what makes me feel that way, and I feel like a major biyatch for explaining this. I don't know if I should wait it out, or breakup with him. I don't know if I'm just being nervous, or its purely intuition. Is there a reason why I might be feeling off about this?