Am I pregnant or just extremely paranoid?

I am in a long distance relationship and my boyfriend surprised me and visited me July 27-August 5, we had unprotected sex during my ovulation week which was the first week of August, he always pulled out but always has a lot of pre ejaculation.. I’ve been testing since he left because I am a bit nervous because we live so far from each other. I am now 4 days late, still with negative pregnancy tests. But for the past few days my nipples have been hurting EXTREMELY bad, and on the outside are a tad bit darker.. idk what I should do.