I am 43; had mostly spotty period (some heavier) for more than 2 weeks?

I am so scared. I have had normal periods all my life. I am not on birth control at all. On June 22, I started my period pretty much on the right day but I had been having this feeling that something was a little odd because I had no "pms" and I had a little more mucus discharge than usual up to that point. I just kept spotting for a few days and then it went to a moderate flow briefly and then back to spotting or light. It had a lot of mucus in it. I had a little more cramping than usual. I think it may have finally stopped but my have been sore the whole time. I went to the doctor yesterday and they did a preg. test; it was negative. She did a pap smear and had me get some blood tests. She said either I was pregnant or in perimenopause or maybe have low thyroid. I told her I had 2 miscarriages before. She said if I am pregnant and having bleeding that I will probably have a miscarriage. I do not want to be pregnant. How can I be pregnant when some of the period had small clumps/weird looking stuff? Maybe I had a miscarriage already? Why are my s still sore then? I'll be getting an ultrasound but they couldn't get me in for a whole week. I'm so scared I can't really live or think right. I need some kind words.