Honey, I too have been there in the past. Now, I am a grandmother and have a great big wonderful family here at AMHD.
First thing you have to do is FORGET trying to be an adult or a parent to your siblings. It is totally your mother's responsibilities. And, no matter what she went through in her youth, she's the one that has to come to terms with it. Why after all this time, did she try and find you? Did she show any interest in you at all while you were growing up and in need of a mother?
You might have very mixed feelings about your father, but he's the only 'parent' you knew and loved, even though he took advantage of you, you probably wish you could forget all this and be with him. Sometimes there are still very strong feeling because you might think he was the only one who ever loved you and that being with him would be better than being with your mom. That says a lot to me. You need to be away from both!
Now, you don't feel loved - either by your mother (who is probably using you as a cheap housekeeper and babysitter) or your step-dad and his family. So, you turned to your siblings and focus on them for some positive emotional comfort. They are way too young and don't know all that is going on, so they also need help... BUT again, this is NOT your responsibility. Let them mess up their own lives if they want, but you get the heck out of there.
I sincerely urge you to seek help and get relocated with another family or home until you are of legal age. You should be enjoying school, not going to work to support a family and you should be able to experience what is left of being a teen. Don't you think you've sacrificed enough?? I certainly do.
Stop making promises to others and start making promises to yourself. Get your life in order, get mentally and physically fit to find your own warmth and happiness in this world - you deserve it and I want you to please start working on getting it.
As you can see, I don't mince words and I do care a lot for young men and women who are used and not given a chance to grow and find happiness in their own lives. And, I do know that if you don't get out of there, things will not get better - not for you, and not for your siblings either. They need help, but from professionals - just as you do.
Now, go see where you can get that support to start a new chapter in your life... and keep us posted. Believe it or not, I just read one of my diaries again, and it made me mad all over again. Read yours, and decide that you want a whole new way of life that will put you in the center. I hope I made sense to you here, it's just that I'm very emotional about things like this and just rattle on.
By the way, poetry is good therapy too - and you're very good at it.
Good luck honey, and let us know what you decide - keeping
one main thing in mind...
NONE OF THIS IS YOUR FAULT, and NEVER WAS!. We are here for you 24/7.
Wishing I could make all this go away for you, but you have to do it on your own... we are here with you dear.