Our son wasn’t officially diagnosed until age 2; totally understand! I found it helpful for me to come up with a rote, 2 sentence explanation that I could rattle off to anyone - something like ‘He has a rare condition called FPIES and can be allergic to any food protein. He is at risk of septic shock. Please make sure not to feed him anything that wasn’t sent with him or pre-approved by us.’
It gets more normaL with time - give yourself and everyone a lot of grace!