fluffycat--welcome to the forum...I hope you'll be able to find some answers to your situation.
I think reversals and the weight needed is different for each individual. Can you supplement your food intake with protein drinks? That could give you the extra calories to put some extra weight on...people sometimes lose a lot post surgery until they figure out what works for their bodies, which might be the reason for your docs answers.
You can find support groups through www.UOAA.org, if you are interested in talking with others. Some find great comfort just meeting others with ostomies.