My teen DD is mostly the same as your DD, OP.
She goes out with greasy unwashed hair, I turn a blind eye. Just like the toddler years, choose your battles wisely and IMHO, this isn't one of them.
She walks to go school and I can only assume she is never late as I have to go to work and can not wait until I know she is ready, so leave the house before her. (Her younger brothers go to the same school and leave 15 mins before her!) I find this hard to cope with as opposite of my personality, eg; airports say arrive 2 hours before departure, I arrive 3 hours early! - But I continue to bite my tongue.
Because she has been getting up so late, she hasn't been leaving herself enough time to have breakfast in the mornings, and sometimes not having her anti-epilepsy medication. This has all been a bit worrying for me, and we did have some battles around the medication. Anyway after several failed attempts to make her see sense, I backed down about eating breakfast and yesterday she fainted at school. Teachers all fussed over her as they thought she might be having a seizure, but no, was caused by her not eating breakfast. She now has a graze on her cheek where she hit the floor, and lo and behold she got her own breakfast this morning without me even mentioning it!!!
Moral of the story, cut her some slack, let her make mistakes so she can learn from them... Teenage years are learning about being an adult and taking responsibility for yourself.....
Sorry if this last bit sounds harsh, but I would not let her demand you can not come onto her floor. Who are the adults in the house? DD is stringing you along a merry dance ......