How to have a normal pregnancy after four miscarriages?

Hello doctor,

I had two live births with my ex-husband no issue with the pregnancies just a high risk for high blood pressure and preeclampsia during labor with my daughter. Now that I am with someone new we are trying to have a child and each time I get pregnant I have lost them. I have had four miscarriages now within the past year and each one was within the first trimester. The longest was at nine weeks. After the miscarriages, I was recommended to go for an infertility test but the doctor only recommended me to take prenatal with DHA and baby Aspirin. So I went and sought another opinion and this doctor did blood work on a hysteroscopy and everything came back normal. I am now pregnant again at six weeks and the spotting starts but no tissue is being passed in its light spotting. I did an ultrasound and the gestational sac was there, but my doctor says there is a little separation from the sac and that might be causing the spotting. I am really concerned and scared out of my mind that every second I go on the net to research. I do not want to lose this pregnancy. I am now taking prenatal vitamins, baby Aspirin, and Folic acid 1 mg. I am worried.

Kindly suggest.