I'm also sorry for your loss mumtoaandj.
I have been in a similar situation; before mc, I could just forgo a few indulgences and my weight would return to what I wanted it to be but since it happened, it's been a struggle! I think that with a full term pregnancy, at least breast feeding burns up some calories but with mc it's as though the rug has been pulled from under us at great speed and our bodies don't know what to do. It feels as though my body is saying 'Ooh, no, we're keeping this fat for the next baby' but I don't want to begin another pregnancy at this weight.
I would suggest logging onto a website like fitnesspal (or one of the others) where you can enter every food you're eating each day (you have to be honest!) and you can see whether you are eating more than you thought you were. I think you may be like me however and if you were quite a controlled eater before, you know whether your metabolism has slowed or you are simply eating more. It's taken me 7 months to shift half a stone as I can't bear dieting and prefer to do things slowly so it stays off but still have another 11 pounds to go. More exercise is the way to go, I suppose.
Another thing to explore is whether your thyroid is slightly hypo and slowing your metabolism (google post partum hypo thyroid for further info and symptoms) It is quite common for the thyroid to be odd after being pregnant, it's a shame that they don't make those who have had a mc more aware of this, as if we aren't bewildered enough. If you decide to get this tested, ask your GP for a vitamin D test too (particularly if you have dark skin) as a deficiency can cause weight gain. Thirdly, you could ask for a hormone profile to be done - PCOS may be playing a part - are your periods regular?
This is what I will be doing to check that something is not out of whack.