Can having too much responsibility hurt a 11 year old?

My 11 year old sister is treated like an adult i am too but that isn't my point. In our small town u can walk everywhere nobody owns a car because well there isn't a gas station for miles and its just a waste of money. We live next to the school and the mall and across from us is the grocery store. So my sister does every ones laundry, she gets groceries, she works on monday tuesday thursday and sunday after school and in the summer she works at a daycare she and her friends own and when she isn't working everyone older than her is so her our 8 year old brother our 6 year old sister and 3 and 6 month old nieces stay with her she goes to the mall she has her own credit card with he own money she is a good provider for our family so am i and our other sisters btw i am 13 also our parents died 6 years ago so our 19 year old sister is our legal guardian so does she have too much responsibility she also cooks dinner and she cooks all the time when nobody is around is it too much responsibility can it hurt her please answer