I don't get it?

Rissa`Ruee ♠

so I've been strictly breastfeeding my 6 week old & it seems like EVERY time after he eats he throws up (like alot).. well last night I had given him 2 Oz of my milk & 2 Oz of formula expecting him 2 throw up I was all prepared, but he didn't spit up at all. So I gave him it again this morning & still no spit up..

but this afternoon I feed him off my boobs & next thing I know after I burped him he threw up! 😣😣 *sigh*