Nervous FTM

I really need advice on trying not to worry. I am the type of person who just thinks the worse of the worse on some simple situations. I worry that my babies heart may stop beating, and I won’t know or that I’m gonna miscarry. I’m a teen mom, and don’t really have a lot of people to talk to since I’m only 10 weeks, and not a lot of people know yet. I have my mom, but she doesn’t really get why I worry about such things since it’s unlikely. I have had a threatened miscarriage at around 6 weeks & ever since then I worry almost constantly. At all my appointments my baby has been perfectly healthy, so I don’t get why I do. Does anyone have advice on not worrying? I truly need it, I’m tired of thinking like this but the thoughts always creep up on me.