Could I be pregnant?

I am having trouble understanding what's really going on with my body. My areolas are larger, I'm having slight cramps, a lot of headaches,and backaches. I had sex with my boyfriend only once and that was during ovulation in March . In April I had a strange period that I had to force to come , it was light the first day only saw pink when wiping and heavy the second day then back to pink the next two days. I'm late for my period by 3 days this month and I took a hpt last month which came back negative. I'm just so confused