Can i be pregnant and is it long enough to get accurate results?

Ok so my last period was aug 25-aug 31. I get my period every month but on different days my cycle is about 36 days. Im not sure wen i ovulate but my partner n i had unprotected on the aug 30 and sept 1st,4,6,10,12,13, n 20th... and he didnt withdraw...i havnt got my period yet but ive been cramping for a whole week now n i would run to the restrm everytime to check if theres bleedig but none yet so far. My r startin to get really sore n it hurts but other than that i dont hav any other symptomd. I did two hpt test last week and it was negative i also did one yesterday m its also negative. So i was wonderin if i can be pregnant and if its too soon to test or should i ume neg since i did 3 test?