I need advice...

Me and my boyfriend dated for 8 months. We broke up because we weren't happy. We started dating again recently. We are really happy. (Although we don't see each other much, we talk on the phone a lot)

We've been dating for about a month now. I'm happy to be with him, but for some reason when I think about him, I get upset. I feel like he's not good for me. I get the urge to break up with him.

Sometimes I feel like I'm only with him because I have no one else. Other times I feel happy to be with him.

I don't even know why I'm posting this, and I don't know how anyone could give me advice. But has anyone gone through this. What did you do? Did you break up with them?