Quoting Cattails:" Told it is hormonal, suspect it's low progesterone, but my insurance doesn't cover testing. I will get ... [snip!] ... get better insurance in about four months, when I start getting the benefits from my job, so I will hopefully get it then. "
Low progesterone is usually found in people with really short cycles (like myself 23-27 days, shorter when nursing (once my cycle comes back at all)).
Low progesterone leads to luteal phase defect, which causes you to start shedding your uterine lining too early (before an egg could possibly have a chance to implant).
People with low progesterone lose pregnancies because the placenta can't attach properly and get nutrients through the lining properly, eventually the lining begins to shed, forcing the placenta to detach, then pregnancy cannot be maintained.