Confused and devastated.

I found out about 3 weeks ago via home preg test and a few days after that, a urine test at my doctors office and a few more home tests just for the hell of it, that I am pregnant. Estimated due date was January 27 2016. Today was my first OB appointment and they took a urine sample. Came back negative. They said I could have miscarried early. They would not do an ultrasound or take blood work. I took another home pregnancy test when I got back home after the OB appointment and it was POSITIVE. I have no idea what to think. Iam so confused and do not know what could be the reason for the negative test result at the OB.