Progesterone Levels

I had a miscarriage in August and we do not believe it was caused by progesterone levels, but there was a time it dropped from 15 to 10. That is within normal limits, but i'm worried that my next pregnancy will have a drop and be the cause of another miscarriage. My doctor is amazing and has said I am perfectly healthy with perfect hormones and I do not need any supplements, but my anxiety is getting the best of me. During pregnancy, if your progesterone drops, will starting supplements at that point help bring it back up in time or is it too late after there is a drop? Any tips you've gotten on making sure your progesterone is good naturally during the TWW?