Hello! Could you please tell me if it's normal? I am 16-17 weeks pregn…

Hello! Could you please tell me if it's normal? I am 16-17 weeks pregnant and when lying on my back and touching my belly, I feel like the uterus moves back and forth. It feels like a solid oval shape on the right side, then on the left, sometimes after sex it rises up to the area of the anus. Is this normal?