A bypass is usually revised to a sleeve if the bypass fails: weight gain, unmanageable vitamin malabsorption issues, excessive dumping complications,... Much like a sleeve can be revised to bypass because of weight gain, GERD, etc,
As others have said, any weight loss surgery can fail if you don't make permanent changes to how, what & why you eat. Post surgical benefits like loss of appetite & your restriction don’t last. They should help you to kick start your weight loss & give you time to assess your eating & establish new eating habits. Sounds like you relied on the side effects of your bypass to influence what you ate. I’d expect your bypass would have failed sooner if you didn’t experience dumping (50-60% don’t with bypass).
You mentioned your tummy has stretched. It does because it is a muscle & stretches & contracts. Can’t believe any doctor would say it can’t. Consistently eating larger portions will cause it to stretch more & contract less. But is your tummy as large as it was before you had either surgery or about the size of someone who never had a weight issue?
The success you have with either surgery is dependent upon you, with consideration of any complications you may have of course.
We all have our reasons for choosing the surgery we did & the effort we put in to make changes are reflected in the success we have or didn’t have. Excluding the life changes that can sometimes sabotage our intentions. I chose sleeve because of the lower risk of malabsorption & dumping. I lost all my weight & more.
I don’t eat like friends & family who carry weight. I don’t eat exactly like friends & family who never carried weight either. I have to work a little harder & listen more carefully to my body (what it needs, how it reacts, etc.) because it’s easier for me to gain weight.
I’m sorry you are unhappy with your revision.