I just saw an osteopathic doctor who said it takes some women a year for the cycles/hormones to become normal after progestin--that seems to fit with what women have written on this forum. I am 16 weeks post and no period yet.
Also, I had depo provera 12 years ago and I remember I felt normal again after about 8 months. I'd had surgery for endometriosis at the same time so I didn't make the connection until last year that it was the progestin causing the exhaustion/brain fog etc.