Negative HPT after a Posive HPT

Ok let me start off by saying I have the condtion that is called PCOS (polycystic ovarian syndrome) therefore its hard for me to get pregnant. I usually have to take provera in order to start my period. I have been exercising for the past month, and well havent really had a period on my own for the past 2 months or so. Well 2 weeks ago I started spotting, and pretty much what they call the breakthrough bleeding. Not enough to really show on a pad, but you could see brownish color on the toilet paper ya know? Ok well it did that for about a week, so I remember last time I did that, my doctor had me take the provera so that I would have a real period. Well it stopped for awhile, then about Tuesday of this week I started spotting again, not red, just brown, and not enough once again to show on a pad. I should have started bleeding truly by Tuesday as I usually start about 5 days after my last pill. Ok well, Thursday night I decided to take a pregnancy test. I took a clearblue easy digital, and to my astonoshmint, it cane back PRegnANT. Well I was freaking out, for years I have been trying to get pregnant, and the docs said that Im probably going to have to do more fertility treatments such as clomid, injections, all that in order to possibly get pregnant. Ok anyway back to my questions, I got the Pregnant on Thursday night, the next morning I got a NoT pREGnANT...I was so confused, so I then went to the doctor and did their urine test and got a negative. So why is it I got the pregnant in the first place if Im clearly not. Or do you think I should wait a week or 2 and retest with a different brand??

I was so excited to see that Pregnant, that now Im just frustrated. What do you think? I really didnt get to talk to my doctor yesterday, I just went in and took the test.Please write back as soon as possible. Thanks you!!