Congratulations on your pregnancy! It is completely normal to feel anxious at every trimester, possibly even everyday. I too was an over thinker during my first pregnancy and it was stressful! The constant googling and checking of the app and keeping a track on body and baby’s growth is all so tiring! Completely get you.
For things you can do on your own to calm yourself, try listening to podcasts. On labour, maybe some on hypnobirthing? It’s helping me a lot during my current second pregnancy. With birth plans and all. There a many books that you can read about preparing yourself for birth and postpartum. I just think it’s best to conquer the fears with good reads and personal accounts from other mothers.
For things you engage with others to bring up your happy hormones (dopamine), do regular video calls with your friends/family members, do some online shopping with your other half (baby clothes, nursery stuff, etc.).
When you’re finally off bed rest, prenatal yoga, walks and meal with good company.
I hope you feel better!