YOU SAID:
i ate two slices of pizza because i wasn't hungry
INTO JAPANESE
お腹が空いていないのでピザを2枚食べました
BACK INTO ENGLISH
I wasn't hungry so I ate two pizzas
INTO JAPANESE
お腹が空いていないのでピザを2つ食べました
BACK INTO ENGLISH
I wasn't hungry so I ate two pizzas
That didn't even make that much sense in English.