A.L.
I'm so sorry about your loss! There's a lot more than progesterone that can cause miscarriages and even more causes that are unknown. Why don't you call your doctor for a blood test; they should be able to check your HcG levels and see if you truly were pregnant this time.
I often feel pregnancy symptoms as my cycle approaches. The symptoms seem to change once in a while too, completely throwing me off and making me wonder. The bleeding itself varies sometimes (I'm only a year older than you). I've also had quite a few miscarriages and none of them started bleeding that close to my expected period.
Hugs to you! It can't hurt to talk with a nurse at your doctor's office, might make you feel better.