She’s just lovely looking!
The general guideline is 1 cup per 2lbs BUT veggies aren’t high in calories so essentially you could give more if you wanted so long as it doesn’t intefere with her hay consumption and doesn’t give her sticky poops. Veggies don’t need to be as restricted as pellets
Romaine, green leaf and red leaf lettuces are great staples. You can also give rocket, watercress, spring greens, pak choi, chicory, kale, mint, dill, thyme, basil, rosemary, coriander and carrot tops.
I wouldn’t necessarily worry about which are high in oxalic acids (tho I believe kale is) If you vary things up each week, you shouldn’t have any issues.
You could choose say, romaine as a base and then just give 3 to 4 other greens; rocket, dill and chicory for example. Then when you run out of those, choose another 3 to add to the romaine; kale, watercress and chicory etc. It doesn’t have to be complex
For what it’s worth, in regards to amount of leaves etc I used to give roughly 4 large leaves of romaine and then say, a handful of rocket (it was their fave), one spring green leaf (as they’re large), one handful of coriander, a few chicory leaves, a few sprigs of dill and a few slrigs of thyme. That was for 2 bunnies (both around 2kg each)