I get where you are coming from. I know you'll love to have your own place when you can afford it. I wonder if possibly storing these in a different area or something could ease your mind some (the towels). Or if you build a good connection with you roommate let her know like three easy suggestions they could do to help make you more comfortable. No you will never be at ease with any of it, BUT you will have some sound mind.
I would honestly talk to your roommate about this. Like they don’t have to change everything, but they can at least change the easy things like not setting stuff on your towel? It might not help, but speaking from experience communication is always better than getting annoyed and not telling the person.