Why do I feel like this...

I’ve been with my bf for almost 3 years and I feel like I’m just waiting for something to go wrong. When we first started dating I found out I had chlamydia, both got treated. We stopped talking for almost 2 months and decided to try things again. But now I feel like something will go wrong. What if I have something else I don’t know about even thou I have been tested and get my annual lady check up. Why can’t I just be happy!!

He’s the best man I have ever been with!! Love him so much but I’m afraid to loose him.