Well, yes I agree totally it's really unfair. What I will do is

No. 1 - stop doing whatever that is not of your own immediate family, take care of your own stuff first.
No. 2 - hold a meeting with all adults in your house, tell them all you said here or more and how tired you are.
No.3 - get them to agree to a fair shared chore schedule
no.4 - type out what's agreed, show it to them and put it on the fridge.
no. 5 - make sure the agreement is follow through

If a compromised agreement cannot be reached, you could then take the next step. If you don't know what next step, you could always come back here for advice.

It is very important to stand firmly on your ground if you don't want people to use or abuse you. No body could if you don't let them.

Hope this is helpful. All the best!