(((Elysium)))
I haven't been down that road. I just wanted to offer you a hug and praise your honesty in reaching out for camraderie!
It's been a year since I worked, but I was a CNA and have taken care of several people in that category. Complications quickly and easily do come up. Gastric bypass surgery is usually only done on people that will carry through with the permanent diet.
The diet restrictions are huge ~ an RN that I worked with had the surgery. It was a huge success for her! But, she would eat one half of a peach and be completely stuffed! The daily diet was just that: a cup of yogurt here, a couple hours later, a few bites of lean meat and small veggies, a couple hours later, something else very small, etc. She lost weight very quickly and felt much better.

That very small diet must continue though...even when a person feels a little happier with their physique. And that's the trick. Staying focused on eating in that new way for the rest of your life.
I don't know much at all about DID and the ability to make commitments like that. I don't know if it's possible. Perhaps getting a dietician and/or physical therapist could help you lose weight more easily and permanently. If you can commit to their recommended changes for X amount of time, your doctor/s would probably be more supportive in the decision to have gastric bypass surgery.
Very best wishes to you!