Not if they are asleep in their beds
I'd pretend to be asleep too if I had a nosy brother checking in on me.
in a room with a window that has no ledge and a locked door with 4 other people in the house
I've crept around in worse situations.
Also there is an invention called a ladder.
Oh and doors can be unlocked.
not to mention her being extremely unattractive
Show us how "unattractive" she is. Besides this is completely irrelevant because an ugly hobo on the streets of New York probably seen more action.
and on her period to boot.
You can have love on your period. Great way to not get pregnant.