Nothing feels worth it.
i was raised to be help others, i parent my siblings and on occasion my parents. i don't feel any joy in doing anything personal and when i pursue personal interests such as art or music, either a; i'm told i'm wasting my time, or b; i feel as if im wasting my time and that i could be doing something useful.
i only want to improve myself for others i feel, and it feels like in the end deep down im always doing something for others because i cant find a reason to do it for myself.
at the end of the day i feel like the only career i could ever pursue would be a house maid or something like that, where i have a solid purpose that im sure to not screw up or have any huge negative impact on those around me.
i feel too stupid to pursue anything larger and my confidence is too low to try anything else.

Just take it one step at a time. Okay? It's okay to have dreams even if they feel like big dreams; it's also okay to feel like you don't have dreams, or they aren't big enough. You just have to ask yourself what you actually want in life.
As for self worth, you can try to improve yourself, evaluate your improvement, and set goals for yourself so you can see your progress. :)
I'm not sure how old you are, but if it feels as though you're burdened with too much to do, you might try to ask your siblings or parents to help. if you don't think it sounds like a good idea, just try taking some time for your own hobbies. If you feel like you're wasting time, think about what you could do with them. If you're painting, you can help your mental health as well as practicing a skill that may be useful if you ever have your own house, or as a gift for a friend, or for a small job opportunity. Music is something that's good for you as well, and if you get good enough other people can enjoy it as well. Right?
Anyway, I hope it works out for you,and turns out well. Come back and talk if you like.