Help! Need to supplement with formula

So my son is 10 months old we have been lucky enough that I have not needed to supplement my breastmilk at all even with a abscess that had to be surgically cleaned out, and now I’m having issues with mastitis and bloody milk and have had to dump a LOT.

My question is what formula have people switched to after being a 100% breastmilk?

I have a supply in the freezer and still will be pumping some so I’ll mix Brest milk with formula to make the transition easier.

Thank you for any help my goal was a year so this is very hard for me to accept.