Pregnancy, thyroid disease and previous miscarriages

Ok well I have thyroid disease and have had a misscarriage in the past six months. I had to have a d&c because the baby didn't have a heart beat and it did not want to release itself. Now I think I'm pregnant again (ironic around the same month I would have been due) and I'm worried. They don't know why the baby didn't have a heartbeat and I'm worried it was my progesterone levels bc of my thyroid disease (the miscarriage baby). I took two tests last week but both were negative bc I think it was too early. I am having all the symptoms of pregnancy, morning sickness, cramps in my abdominal region, strong sense of smell, hungry all the time and having to pee constantly. And to top it off my period is late by three days. Does anyone have any advice for me who has dealt with this before?