Although her hair is beautiful, I can see how it just isn't the look for her right now. I wouldn't have my child go to school with hair she hated. If it was me, I would try one of these options:
1) Cut her hair in between, to make it less big. My brother has the same hair as your daughter( but he wore it a bit shorter). His hair was cut in between so it had the curls he wanted ( beautiful 3c curls) but it was not big. The moisturizing you are doing today will stay the same.
2) Do a texturizer, if you allow it. If she doesn't like it, then this could be a problem but it will cut down some of the bulk. She will still have curls, though, they will just be more streached out.
3) You can try different protective styles but you are doing this already, so I don't see how it would be much different. I see a lot of girls with braids ( many of them, instead of one). I personally would love this style for that age but it is up to her.
My son is 9 and has hair like that too. He wears it short but I like to let it grow a bit to show the curls off a bit. I am glad he like it. I always tell him how cute his hair is. When he gets his hair cut, he always wants a number 3 blade, which I am glad he does. I hope he never tells me he wants a close shave and if he does, that he does it because that is what he wants and not bc he hates his hair. I struggle to keep it moisturized.
Please don't let her hate her hair, tell her that you will work with her to try different things. It would be great if you could talk to the school about the teasing but I think it is too late for that.
I have a question for you, what is olive oil cream? Sounds like something my son needs in his hair. I use straight olive oil on his hair.