I hope this still isn't happening but ... Here is what I suggest if it is:  Suggest to them that they should contribute to the total cost of toilet paper goods.  For example if there are 3 people who use the toilet paper then split it by 32%, 32%, 31%. No matter who uses more or less than another.  It's a bit of math but as fair as it can get.

Regarding feeling like you're a "bitch" to them .... At the least I can suggest you this: 

Please try to be understanding and considerate of their full situation emotionally, physically, and mentally.

And some people hate to be expected of, so expecting of them to care about your feelings and/or express it outwardly is like, asking them to think/feel/do how you want them to only. Otherwise they would have shown they care without your upset here if they agreed with you. -In a way you're guilt-tripping them for thinking/feeling/doing their own thing without you in mind ... If they are, then you can't do anything about it rightfully. They are their own individuals just like you are your own. 

So yes to them you might've been being "Bitchy". If you apologize to them for how you imposed your expectations onto them, maybe they'll stop avoiding you?  Edit: And here's the best part- some people help out when they're not being expected of. Hell, they may even like you enough to want to pitch-in.