my cat has a weird relationship with food

to give context, i have a diabetic senior tom cat. he has fiv and is also toothless. he has issues with food where he throws up the food because he scarfs it down, but only when its in a bowl. if its in a free feeder or gravity feeder, he doesn’t throw it up or scarf it down. however, because hes diabetic and i have to do his insulin injections after his meals, i can no longer have him graze from a free feeder. ive tried a slow/puzzle feeder, and he still eats it too fast. ive gotten all the bloodwork and everything done for him, and there is no gastrointestinal issues. i am not sure what to do. his regular bowl is elevated while the free feeder isnt, so thats not the issue either. he refuses to eat wet food as well for some reason. im just at a loss and i dont know what to do. do y’all have any advice?