Can supplements and tests help alleviate a Miscarriage?

Dear Professor Winston,

I have had 2 back to back miscarriages within 6 months, one at age 33 at 8 weeks, natural miscarriage after being diagnosed with a threatened miscarriage at 6 weeks.  Both were after seeing a strong heartbeat previously but resulting in bleeding/spotting before loss in both cases.

I have a 9-year-old son who was born when I was 28, only issue during that pregnancy was a PV bleed at 16 weeks which they thought was a blood clot but could not say for certain. I am now 37, I have been tested for lupus and clotting, both were normal. Partners sperm has also been tested with no issues found. I have to start progesterone suppositories when I next get a positive pregnancy test.

Is there anything else that I should be thinking about and/or looking into for example having tests or taking supplements etc., before trying again as I really couldn’t handle another loss.