How to deal with this? [kinda long]?

We recently got another "foster child" for my family about a month ago [about 17]. On one hand we are pretty okay and cooperate like we are "regular" sisters. We talk about everything and stick up for each other. But at the same time I do find living with her is rather annoying.

She has a bed wetting problem which I am normally very polite with and if she forgets to put her sheets in the washing machine I will remind her before we leave the house but the thing is sometimes she refuses to listen to my reminder and just leaves them there. Not only do the sheets after hours of being left there make the room smell like pee but they also have a very unpleasant "feminine odor" on top of that.. When the room smells like this normally I will ask to wash her sheets, scrub down the bed, etc so the smell is gone. I never make it a big deal to sit there and make fun of her because I wouldn't want someone to do it to me. Her social workers and everything have witnessed the smell for themselves and all ask how can I deal with the smell. Lately, I don't. I will sleep downstairs on the couch because I normally don't fall asleep til around twelve AM anyway.

Another problem I have with her is the fact that when she is on her menstrual cycle she is not too clean about things. I have found used pads on my dresser. To me I find that disgusting and inconsiderate seeing as the trash can is only a few paces from my dresser.

These two are the biggest problems I have with her and I don't wanna approach them the wrong way because I did think about it and some of the stuff she says does kinda give the impression that someone did something sexually that they were not supposed to do but at the same time I do not think I am asking too much especially since I am not trying to make fun of her or anything like that. How do I deal with this?