I know how much you must be worrying, exhausted & stressed. Go talk to your GP & he will give you a referral. Even if it turns out she is just attention seeking, a professional will be able to give you the right advice & tips on how to either conquer it or hopefully reduce the severity of it.
My DS has very mild OC and we cope quite well with him, my nephew (15.5 yo) & sister (42yo) has it quite severely and I know how frustrating & exhausting it is. both my sister & nephew though have other mental conditions which really make controlling their OC quite difficult (&makes it worse to a degree).
Seek help now while she is so young incase it is OC. It may even be an underlying anxiety issue in which case a childhood psychologist (or similar)will still be able to help.

To me It does sound very obsessive (like with her cup) but being that she is insisting you come & check on her, there may be something making her anxious (any nightmares?)

Hope this helps you, as I said, my son is only very mild so I'm not the best person to have replied but I just wanted to offer you support. I really don't think she is just seeking attention, but I don't know enough about it to pass judgement ITMS.