Best bottle for breastfed babies?

My son, has been exclusively breastfed, not quite 8 months old won’t take the bottle. I am doing this because I have to go back to work. I’ve tried different bottles. The last formula he was on he would throw up. I called the doctor and he said to put him on the Gentlelease one. But now my son is refusing to eat. I’m keeping fluids and watching diaper output. The doctor said to just wait it out he won’t let himself starve, but he is refusing to still eat, even solids. I don’t know what to do anymore. I’m in tear honestly and feel like a failure. My breast milk supply is all but gone already. Please I need advice.