Short answer: Get out ASAP.

Long answer: I lived thru a similar situation at a similar age, and I can clearly identify that time as the point in my life when MY life truly went to hell and never recovered. I know what you are going thru, and I know just how much worse this could get for you.

I'm sorry you are having to shoulder so much, and are not even being appreciated or treated fairly. NONE of this is your problem or responsibility. Not your parents' breakup, not your mothers' life now, not your two younger siblings, not your fathers' behavior, not the financial issues, none of it. I get that you care about your mom and your family, but this is hurting you and has the potential to really throw your life off track.

You were not married to your mother or father, you are not the parent of your two younger siblings. You do not have to take care of them, period. Sounds rough? It's not. You are entitled to continue to live your life in the way that best supports you and your separate, individual life, even if that means moving away (physically, mentally, emotionally, financially) from your family and their needs. Their needs are NOT the same as your needs. You are putting their needs before your own (and are being encouraged/ asked to/ expected to) and suffering for it. You said you also moved back home not just to help but for your own financial issues, but this situation is too much to your detriment now. And it could get worse.

This back-and-forth, up-and-down cr@p you are getting from your mother only serves to upend your balance and keep you focused on how to do more, do better, do it "right" for HER. That's taking care of her, not you. There is no way for you to do everything just right or good enough (whatever that is), because this is not about you and something you should be doing. You can't fix this, any of it, in any way, shape or form. THIS IS NOT YOUR PROBLEM. By asking so much of you, your mom is making her problems your problems.

It's not going to work to live at home to try to handle your own financial situation while this is all going on. If your mother is like this now, it will likely take years for her to get her act together. She could get herself straight at any time, but it's probably not going to happen soon. She is likely only going to get more and more dependent on you, emotionally, financially, etc.

Will your mother freak out at the possibility of your two siblings leaving and do all she can (covertly, overtly) to get you to stay with her so she doesn't have to be even more alone? Will she do that when you try to leave?

What happens in two years when your 16 year old sibling finishes high school and wants to go to college? Will s/he stay home and take over so you can leave and go pursue your life? Will your mother insist this child sacrifice their life for her and stay to help her? Will you insist that your sibling stays and sacrifices for you? (not saying you would do that) Or will you stay and continue on while they go on and have a full life (like you should be free to do)?

Same questions for your 13 year old sibling in 5 years (and 5 years can pass in the blink of an eye, esp. when you are living like you are and doing all you're doing).

After you get into grad school (straight A's!!), do you plan to continue to live at home? 'Cause this is gonna break you. This is not going to work long-term. You will suffer for it. I don't know much about bipolar, but I'm sure stress is not helpful. You sound seriously stressed and overburdened. I think it's amazing that you are handling everything as well as you are. And I think it stinks that you are having to handle all this in the first place. This should not fall on you. This is too much for you. You are being asked to take care of too much. This is not okay.

You can't get your mom to shape up or get better. You can't get her to change her reactions or responses to you. So what do you want to do? How much longer do you need to stay? Do you have an end date in mind? What is that dependent on? Can you make that happen for sure? You can't stay open-ended, with no date in mind. It sounds like you are dealing with more than just being treated as a child. You are being asked to carry your mom's problems and her life right now. Not fair to you at all.

I agree with everything hvert posted.