OMAD will lower the metabolism as your body isnt needing to process food as frequently, along with the lower metabolism as we get to lower weights, so the big question here would be if youre actually eating the calories that you need now (/needed at your weight & metabolism after fasting) , and not the calories that your previous weight needed. I feel like most of us, myself included, accidently eat more than we need because the amount of food we need really isnt anywhere near as much as we assume it is.
I dont mean to sound rude here but its just to assess the situation- you say you got to heavier than when you started, so it makes me feel that because you started gaining weight, even that first 10lbs or so, and at that stage you didnt address it nor lower calories before it got higher and higher, there may be a bad relationship with food here or a lack of calorie intake awareness