Help my mom dosent ever let up?

she makes me watch my 2 month old baby sister pretty much 6:30 am till atleast 9:00 pm (usually later) pretty much she works some days 6:30 am till noon (some weekdays that is) then 5:00pm till 9:00pm (mon thru thrs) my baby sister is very very fussy and loves to scream (usually cuz she has gas and her belly hurts)((yes we use milicon idk how to spell it drops) while watching the screaming baby im expected to clean while my step dad sleeps (anytime he isnt working) and my brother (12 yrs old)plays video games then i am screamed at for anything not perfect or not finished or not done fast enough and i never get a thank you on top of that my brother makes messes one after another leaving plates and food and toys and things around the house that im expected to clean up further more he has ocd and add so he is incredibly irritating on top of it all i have a dog and 2 cats the dog sheds so bad that there is clumps of fur all over if i dont vaccume daily and cats who crap all over the basement we have flies (bad) which i am trying hard to get rid of and all of this is too much this is supposed to be my summer VACATION all my friends are mad at me because i NEVER get to see them i just dont know what to do anymore (im 16 going to be 17 november 1st)