Am I having a misscarriage?

I got my period on 11/27. I had unprotected while I was ovulating in (12/11) I took Plan B on 12/13. I ended up getting me period on 12/30 so I thought I was fine. Ive taken Plan B before and had no problems. Well as soon as my period was done on 1/5 I started to bleed within a couple of days. My were super tender. I finally called my doctor and took an at home pregnancy test... and to my surprise it said POSITIVE.... Ive been bleeding ever since. I got retested at my doctors office this weekend and the test shows up positive. I had an ultrasound done and the results were nothing visible. Im either to early or theres nothing there although my test was still postive. Im still bleeding today... am I misscarrying? I have to do some follow up blood test tomorrow but I dont get my results till Wedenseday... Im very inpatient... does anyone have any advice?