Scared of losing baby after 18 weeks I need some reassurance

I had a miscarriage last year so this pregnancy has been hard to enjoy. Even after 12 weeks I'm still scared. I'm over 18 weeks now, and I'm so scared of something going wrong like having my baby too early or having a still born. Or some type of heart problem. I don't know why I'm so worried honestly. What're the chances of something going wrong now? At my 13 week US everything was perfect and baby was measuring ahead even. But I'm still so worried and don't know how to enjoy this time. Any advice?