Talk to me about MMC

Kailey • A girl in love with her hard working nurse • 3 angel babies & a Rainbow Baby Girl Hanalei! Pregnant with a second little miracle.
So I'm 8 weeks 4 days (2 weeks 4days past the furthest I've been able to carry prior to a miscarriage). I feel nausea all day (in my stomach but not throwing up) and have extra saliva, tender boobs, slight cramps now and then, back pain, major mood swings ( I cry all the time now) and yet even with these symptoms I worry everyday about seeing blood on my TP or a missed miscarriage.
I've had two healthy, positive US with strong heartbeats last one measuring 171 at 8 weeks. The size and growth of baby is right on track and my dr moved our normal two week check to three weeks so I can do my genetic testing at 11 weeks 2 days.
So why, even with all this positive information and I still so worried about a missed miscarriage? Can it happen when everything looks so seemingly healthy? I just want to enjoy my pregnancy .. I my previous miscarriage history makes it so impossible 😔
Speak comfort to me ladies. I don't want my stress to hurt my sweet Little Rainbow Bean.