Low hcg but saw gestational sac...no idea what's happening

This is my first pregnancy, it has been the craziest past week. 9 days ago I got 2 BFP and my hcg was 54 approximately 14dpo, the doctor wanted to get it rechecked so Monday it was at 88, it didnt double and I was freaking out. I got it checked again on Wednesday and it was 129. The RE wanted me to come in and get and U/S and he couldnt see anything and pretty much told me he thinks it is an ectopic and to recheck labs on Friday which was 211, it didnt double again so I went back to the RE on Saturday and he could see a gestational sac. He said if he didnt see that he would have given me the methotrexate shot but since he saw that he wanted to wait and have me come back on Tuesday. He hasn't been optimistic at all and said I could have a ectopic with a intrauterine pregnancy and I may need surgery. He couldnt verify that I had an ectopic and said it could be a fibroid. He pretty much is making me think I'm going to misscary eventually because this is not a normal pregnancy. Has anyone ever been though this before? It has been the most stressful week and have no idea what to think. 😥 maybe I didnt ovulate till a little later and I'm earlier then what i think I am? Any thoughts?