What's the name of this book?

I'm trying to remember the name of a book I read when I was a little kid, about 12 years old. When I got the book it was used and several years old. It's a story about a family of potato farmers in ireland. There's the mom, dad, the oldest daughter, the little brother(I think), and then the youngest sister. I think it takes place during the irish famine. Their crops die, and plague is rampant through the country. The parents leave the oldest daughter home with the son to take the youngest daughter to a doctor because she has caught plague. The story is told from the point of view of the oldest daughter. In the end the youngest daughter dies. I think the title was somewhere along the lines of The potato Children. I can't remember much, please help.