Just wanted to share one other possibility for consideration that I haven't seen yet.
I had a very similar experience and was really regretting the surgery - nothing stayed down - not even vits. By 7 weeks out I was so dizzy, weak and tired that I called my doctor who ordered another upper GI. I had to have a little bowl nearby because I was sure the barium wouldn't stay down either!
Long story short, the test revealed that the end of my sleeve that goes into the small intestine was too small. Barium that should have passed through in 5 mins took 2 hours to show any movement!
My Dr said this happens in about 5% of sleeves.
I had to go back into the hospital and get an endoscopy under general anesthesia where the doctor inserted a gizmo into my sleeve that contained a deflated balloon. He inflated it just enough to stretch that end and enlarge the sleeve exit hole to the intestine. Its been 3 wks now and I can tell the difference - although I'm all goofed up on what I should be eating since my first 7 wks were milk, pudding, water and coke ( the only things that usually stayed down).
In retrospect, after my sleeve in the hospital, I was unable to pass gas at all even though everyone else that day could. After my endoscopy to stretch the opening, I was passing gas coming out of anesthesia. So if you can remember back to your surgery and the gas factor...you might be one of the (un)lucky 5% like me. Hope you find the solution for you that works