How do you keep calm?!

I feel like lately I've been worrying so much. I am at 10 wks and was told at 8 wks that we were expecting twins. They both look very healthy heart beats at 155 and 157, I haven't experienced any intense cramps or bleeding ... yet I am constantly feeling like something is wrong with one or both. I don't know how to turn it off. I have no way of knowing 100% till April 5th at our 12wk apt if everything is OK. I mean I feel like it should be, so why do I keep stressing. I hate it!!! Any advise would be greatly appreciated!!!