Taken Loestrin When Period Started. Now Bleeding Stopped. Pregnant?

I started my period 5 Mondays ago and had it up until last Wednesday.. When my pd started I had started taking loesterin fe as per my Gyno . During the 2nd week my pd stopped the next day I had a huge huge red thing come out of me which I assumed was a clot (bigger than an egg), then my pd started again and I had it for 2 more weeks. I went to Gyno the other day and she said my lining was so thick I should have had my pd for another month but it had stopped the day bfor and haven t had it since. She was worried I was pregnant or miscarried but urine came back negative so she took blood to be sure. Could I be pregnant?