Infant son newly diagnosed

Good evening.
Here a mom of a 9 month old baby. Diagnosed at 7 months. Day after 6 months shot son went into DKA. Exclusively breastfed. At that time never ever sick before. Not even a runny nose. Nothing. Antibodies-all negative. Neonatal panel to see if it is genetic - negative. Dr still wants to treat as T1D due to his presentation. Currently has a pump. What works some days doesn’t work other. Diet mostly breastmilk. Still trying to figure out what to feed. Sometimes high and hard to get down. And others working hard to prevent dropping. So confused. Recommendations? What other test should I ask for? What else could it be?
Hoping to get all this figured out. And a miracle :pray:
Thanks everyone.