What Causes Missing Periods, Cramps And Sore Nipples?

Hi I am 11 days late for my period so I did a few pregnancy tests the first 2 I did were clear blue and both had a very thin faint positive line and I also tried a first response and that was negative I've been having cramping and my nipples are really sore to touch usually my breast hurt but not my nipples could it be to early to show a positive on other results