Need advice!!

My last menstrual was April 25-May 2. I did the deed on the 17 but when I took a test, it's been negative. Going on almost two months without my cycle and since Sunday I've been having sensitive/sore nipples but no blood in sight or any cramps.

My coworker say I should get a blood test but my mom thinks it's just stress. Somebody even suggest I'm ovulating.

What's going on?

Has anybody ever gotten a BFN on a HPT but had a positive blood test?