My HPT has gone Crazy!! Please Help..

I took two hpts yesterday. Under dr. request to be sure that they hadn't missed that i was pregnant at the time they put me on my fertility meds.. Well I am 2DPO. My first HPT was a BFP the next one i took a few hours latter was a BFN. Then I used FMU today when I woke and it was also a BFN. I called the doc. office and they just told me that when I got the chance to go to the health center and get checked if it was Positive to call and let them know. My question is, could it be possible? I didn't have a AF in July, is it possible that maybe I O anyways? Or could I have O before I was supposed to and didn't know this mounth, because I did have an AF. I took prometrium this month to have it. I'm really confussed on why I would get a BFP then get BFN's. Can you please help me, or explain to me why this could of happened? Thank you so much for your time!