Almost 34 weeks Pregnant?

I have a Question, I am having Twins, I will be 34 weeks on Wednesday, I have been having this feeling that if I stand to much it feels like everything from inside of me is just going to fall out, so to say. I know that because there are two babies in there that they are going to be heavier and take up a lot of room, but geeze, It seriously feels like if I dont sit down quickly that something is going to fall.. I was j ust wondering if anyone has ever expenenced this before.