Help!!!

I’ve been having sex although I use a condom everytime. My last period was April 11-15. I haven’t had one yet this month and took a test that came back negative. Although my boobs hurt extremely bad and are getting noticeably bigger, I’m cramping, and also if I sit for a long time and suddenly get up i get dizzy.

Am I over thinking this and stressing on it or is it just a period coming?