S.W.
I'm sorry this is happening, and I'm really sorry your doctor put you through so many tests.
I had a blighted ovum with my first pregnancy. I had no idea this was possible, so being told this was no fun. I only had one ultrasound, that's all that is needed to see that this is happening. I was given the option of having a D&C or waiting to see if the miscarriage would occur normally. I was allowed to wait as long as I wanted to, unless I developed other symptoms. I ended up waiting almost three months. During this time, I bled off and on lightly and had other uncomfortable symptoms from the changing hormones, like bad acne.
Eventually, I got tired of this and had the D&C. It wasn't comfortable, but it was over quickly and I felt back to normal in a couple of days.
I would get a new doctor. He/she should be telling you what they are seeing and what is going on, doing fewer tests, and giving you options.