Could I be pregnant or have other related health issue?

[Pcosmommyto1]

I am 27 years old and was diagnosed with pcos at 18. After I got married we were able to conceive without even trying. My dr had me on metformin to help with the pcos and I had lost aprx 30 lbs before time of conception. I now have a healthy 4 year old. I've gained 50 lbs since having my son and just started metformin again a few months ago. I am 13 weeks late. No sign of a period at all. My first month missed I took 2 hpt... negative. Second month missed I took two more....negative. So I figured it was because of pcos and haven't taken anymore. I went to my obgyn for my yearly checkup and told her about my missed cycles. She asked if I thought I was preg and I said no because of the negative hpts. She did my checkup and while checking me out she asked if I would be upset if I was indeed preg. I told her no. She then said everything looked good but she wanted to send me to get an ultrsound. I asked why and she said to check out the thinning or thickening of my lining. She also asked if I was having acid reflux, bloating, etc.... all of which is a yes! (I also have gained 8 lbs in the last month or so). So now it's a waiting game to find out what's wrong with me.... could I be pregnant with negative hpts? Is it something serious like hyperplasia, tumors, etc???? I'm having mixed emotions and thoughts. I love my dr. And maybe I didn't ask enough questions at the time but I'm very confused on what she was maybe thinking? Any advice or thoughts would be appreciated. Thank you!