Spinach?oxalic acid?

my rabbit doesn't get vegetables everyday because my meatball of a mum forgets to get them but when I do he gets one type of leafy greens for a week and then it changes. is this ok? I know you shouldn't give too much spinach because of the oxalic acid but I don't want to just throw away good vegetables. the week after I feed vegetables with high oxalic acid I will feed a leafy green with a low oxalic acid.

My bunny does not like spinich, though last time I tried giving it I ate the rest myself. I eat it cooked or in salads.

Spinach is high in Calcium too. I prefer Spring Greens for my rabbits.