Unintentionally toxic?

I don't want to go on too long a rant but I want to get a few things off my chest...

I've been living with my boyfriend and his friend in a two bedroom apartment for about three years now. We all mostly get along since we've got similar interests and are all around the same age. But it's really starting to be a struggle with our roommate... In the three years we've lived together, she has lost her job four times and is currently unemployed for the fifth. In all instances where she hasn't been able to afford rent, I've covered for her. For months at a time if need be until she got back on her feet. I had a decent amount saved up from when my father passed away but at this point my funds are really starting to run low...

And now I'm just really getting upset because me covering is just what is expected of me. At the start I wanted to be really supportive because she's trans and had to leave her verbally abusive family. But now I just feel used... For the months she'd be unemployed she'd look for jobs but not really take on any of the extra house work. At one point I was cooking dinner for everybody nearly every day of the week despite going to school and having a job, until I put my foot down. I take on responsiblities because that's just how it's been for me since my father got sick. After he passed away, it was just my mother and I so I would help cook, do laundry, vacuum things like that without being asked because I know my mom worked long hours.

I'm just drained... She has ADHD as well so I was feel like I'm a mother hen cleaning up after her. Even after we've asked her to turn off lights when she's out of the room, she leaves them on and the other night she just left the kitchen sink running. I went to make myself some tea and noticed before it flooded the whole kitchen. When I try to talk about why I'm upset she just gets defensive and starts accusing me of things. We talked to her about asking before she eats certain leftovers. It makes sense to us that if you make the dinner the night before, you get first dibs on it the next day. She said she was scared to take things from the fridge now but she totally still just takes leftovers without asking. I got upset that she wouldn't take on any extra work unless prompted or already saw I was doing something. When I tried to talk to her about it, she got upset and said that I'm always the one with the plan. But at the end of it all I feel like it's the role I've been forced into. When there's a huge mess in the bathroom or there's mold growing I've been the first one to do something. I have to make sure there's enough to pay the rent because it always comes out of my account and I send it through the mail. I've got the landlord's address written down on a board so I can easily write it each month and one day she even asked me who that was...

She just seems blind to all the responsibilites she puts on me and when I do bring things up she turns it around to make me feel bad... I don't think she's intentionally being manipulative and she isn't outright mean to me. But I still feel like a parent and it's worsening my own depression. She eventually does pay me back for the months she misses but it feels like a cycle I'm not allowed to break from.

I'm sorry that I went on such a tangent, I just can't keep being held responsible for somebody else when I'm struggling so much too...