eventually your body will come around but the problem with using other artificial hormones (like progesterone cream) is that your body will do the same thing it did with mirena...it wont produce as much (if any) progesterone because it's getting it from an outside source. The body doesn't "forget" how to produce progesterone with these things, it is quite smart actually and it stops manufactoring it on purpose bc it says "hey, i no longer need to spend energy creating this hormone since i have enough [from an outside source]." Sadly, all you can really do is just wait for your body to start regulating itself. This is a problem with most types of hormonal birth control. Personally, i was on the pill and still had this issue. again, bc the body wont waste energy manufactoring something it realizes it doesn't need. Waiting is the best bet. they say most womens cycles will return to normal within the first 6 months, typically within the first 3 (maybe even sooner). I wished i would have listened to that coming off the pill because i got pregnant my first cycle off and then i ended up MCing, and im quite certain it was bc of low progesterone. Had i waited, i wouldn't have had a loss.
Im not sure if you chart BBT or not, but i would *highly* suggest it. It can tell you many things, not just when you ov, but it can tell you how long your LP is, which would be a good indication if you have sufficient progesterone levels or if it has increased month to month.