Medical challenges: Graves’ disease

Baby #5 is 6 months old and I’ve been diagnosed with Graves’ disease. So far all of my kids nursed into toddlerhood on demand with almost no bottles and 0 formula. I’m only saying this because now I have a medical challenge and I’ve been placed on medications that require he not nurse for a few hours. I held off on starting until he hit 6 months so I could give him solids, and even then I was unsure, but my symptoms started to make it hard to function and I was at risk of having cardiac issues. Right now I’m taking methimazole before bed and I just have to try to hold him off for 3-4 hours (which already is difficult). Now they want me to increase my dose and add propranolol. I’m starting to wonder if I need to try to give him some formula in the evening so he can potentially make it the 4 hours. I know it is digested slower and I could mix it with breastmilk and nurse him on demand the rest of the night and day. Last night he was miserable at like 2.5 hours and I tried to calm him but he just wanted milk 😢 Any ideas?