You're right; it's illogical, but it's understandable to feel like that! I know I would. Don't worry, you obviously had some nasty issues else you would've have had such great help to begin with. Well done for kicking butt!

And yes, losing or raising weight too quickly can be bad, (taking in nutrients too quickly and slowly--I believe--is also unhealthy and needs to be done gradually, but I'm sure things were done just right for you) ... but, as far as I know, it's mainly just not to healthy for the skin, but only aesthetically, I believe. So, stretch-marks, really. I wouldn't worry too much. You are doing wonderfully and should be proud of yourself, IMO.

Go you!