Suppose to start tomorrow but worried.

Suppose to start tomorrow but I'm worried that I won't BC during this week I had cramps . like a few actual period cramps. Then when I have sex with my man it feels like his 🍆 is in my uterus kinda like a little pressure. My periods are always on time and sometime I get cramps but not like the cramps I was feeling. And my boobs get soar as well before I start and thats how they feel now. I'm just wondering why I've felt the pressure in my uterus when we have done it two days in a row now???