Twinless twin?

I got a BFP in early march and miscarried at 9w5d on April 20. In my follow up ultrasound, all that was noted was a thick endometrium and a 3cm mass. Now, I am having phantom movements, cravings, breast tenderness,  a little bit of weight gain, and I'm so so nauseated. I have had light sporadic bleeding since my MC, but haven't been able to go back to the doctor because I lost my insurance. Several people have mentioned that maybe I just miscarried one twin and the cyst was the other baby. I haven't had any follow up yet, so I don't know. Has this happened to anyone else? What do you all think? Thanks in advance. :)