BFP - Doctor Confirmed - Then BFN ?!?

Ok so at 10 and 11 DPO I got a BFP on multiple FRER and Clearblue digital tests... Went to my regular doctor and they confirmed with another urine test that indeed I am pregnant. Based on my last period and ovulation this cycle, I am about 4.5 weeks right now. I'm scheduled to see an OB on 5/3 when I'll be 6 weeks. Took a digital test today for the hell of it and it said Not Pregnant...why?!? I've had no bleeding or abnormal pain or anything whatsoever. Should I be worried? I'm freaking out a little bit.