I need help with this pregnancy emergency!!!!!!!!!?

alright so im 5 days late on my period, and have been so sick to my stomach for a week and a half, and have had really bad headaches with it, my lower back has been killing me for 3 days, and have been peeing a little bit more than usual, ive looked up everything that could possibly make my period late, stress..i don't have any, medications...im not on any, coming off the pill or starting the pill....ive never been on it, illness... im not even sick and haven't gotten anyone sick, menopause...im only 20 years old i highly doubt its that, change in cycle...ive had my period since i wa in 5th grade and this has never happened to me. i have had unprotected in the last month a few times, and about a week and a half ago, almost two weeks really i went to the bathroom and had some tiny little blood spots, but only for one day, it was like nothing though. i took 2 pregnancy tests the day after i missed my period and they came up neg, but everyones telling me that was probably too early for the hcg to show up, and its been 4 days since then and still no period.....what do you think is going on?!!!!!