Omg with my first i was so overwhelmed with everyone else's input!! Like:
Don't reach over your head, it will lead to cord strangulation
It's bad for the baby to lay on your back during the entire pregnancy...
Don't listen! You are fine!
I slipped off the step of our SUV and hit my stomach on the infant car seat base while putting our older child in her seat in the middle (base was for child that was the then current youngest) I was terrified that I had hurt my baby because it left a nasty bruise on my lower stomach but I never bled and my doctor told me that there is a good amount of protection around baby! Simple tasks won't hurt baby :) Falling was always my biggest concern
Baby is very well protected by the uterus, amniotic sac, even the placenta offers some protection. Don't stress, stress makes things worse. Try some yoga or meditation because it really helps relax and it helps throughout the pregnancy. Like stated above your body knows what it can handle and will send you signals, just listen to your body, and baby and all will be fine.
What might help is to read more regarding tips of what not to do when you're pregnant. Most of the time your body tells you if something you did has been too much. So listen to your body and follow the basics; no heavy lifting no high intensity excersising etc.
This is my 3rd and believe the baby is really well protected inside us :)
This is my first and I started out feeling that way, but as I progressed (33 wks), I feel less paranoid about twists and turns. I just move slower and try not to strain, but the uterus is super strong making the baby well protected. I worried when I sneezed, but since I've been with allergies for ever, everything is good so far. It's normal to feel nervous. Good luck.