I think I am retaining water as I took a lasix last night and dropped all 12 pounds of what I have gained. I am going to the doctor's today. Hopefully he can figured it out.
You could have retained tissue there. I'm sure I did but it finally came out and then I dropped 2kg in about a week (1kg from each boob I reckon). Do you have any pregnancy symptoms remaining? You could do a hpt and see if it is negative. It will be if your hcg is below 25. That's what I did.
I think mine took six weeks to go down to zero, but they also did an u/s to make sure there was no tissue, etc. still there.
It took mine 8 weeks to get down to zero.
I had almost the same thing, though I didn't have my progesterone tested. It took forever for my hCG levels to go down after my miscarriage, and finally they decided some small amount of placental tissue was still there, causing the continuing hCG readings. Had an ultrasound-guided D&C to take it out. I'm surprised that your doctor has not suggested looking with an ultrasound to see if all the tissue has cleared.