Im 5 days late for my period negative hpt help???

im 5 days late for my period took a pregnancy test this am and its negative why and how?
im constantly peeing my boobs strike pain few times a days I feel nausea every am I'm sooo tired this has been like this a 1 1/2 weeks.
I got off bc (birth control pills) November/December from October to December I was getting my period 2x a month January it was regular I started having unprotected sex feb 9th till Feb 23rd my fertile days were feb 10th till Feb 15th I think I had implantation bleeding on feb 20th I only spotted once.could I be to early to test?