am I pregnant?

Okay, I've posted on here a few times about this, but I suspected I was pregnant. I took a walamrt test and I got a suuuuper faint line but it didn't show up until an hour later! I took a second, and it was negative, then took a third test.(which was more expensive) and after the 3 minutes it was negative but an hour later, it had a faint outline (by that I mean it wasn't a full line, just outline of where the line should be. I final caved, and went to family planning to be sure what was going on. none of the ladies have seen anything like it, and I took a test there and it was negative??? super confusing right? WHAT'S GOING ON? I've been having sharp stomach pains, and nipple pains (tmi). I can't really say when my next period will be because they're off the wall. can someone help? DYING for answers. :(