Stubborn stall

Hi! So I have been losing weight the good old fashioned way for about 7 years now. Lost majority on keto and somehow was able to keep it off and transition off keto, thanks to addition of metformin and lots of exercise. I have since lost about 30% more on tirz and sema, getting closer to my goal, which I had all but given up on. That said- I lose very very slowly. I’ve dropped 35 in 12 mos but stalled out months ago and just maintained. I had topped out at 15mg tirz and started stacking, got up to 1.5mg sema and rotated. It was too much- I shouldn’t have to take that high just to maintain. I stopped for 3 weeks, added back tirz at 5mg and now up to 8mg. I’m not losing, not gaining, but do feel like I’ve gained some abdominal girth and lost some of the good side effects I liked. I’m ready to try Reta, I want to get the last 10-15lbs off. Do people tend to do better stacking or just cold turkey switching? I am 41F, 150lbs.