Missed period

I havent had my period for 27 days took a test and it said negative, but 4 days ago I had unprotected sex, it was like put it in for 2-3 thrusts, not even close to him finishing and I told him to take it out and put a condom on, now I have light spotting which I know can be caused by implantation... idk what to think, and I just need some honest opinion