Does anyone know what this book series is?

A few years back I remember readin a book series of 3 parts. I dont remember much about it but I'll be as detaild as possible. It was a story of girl growin up durin the pioneer days I believe. Her mother had a baby and the girl also had a younger brother. The mother died I think in childbirth and they travelled with the father searching for a place to live. There were indians in the story etc. I remember that in the 2nd and 3rd books they temporarily lived in a lodge run by a heavy lady who left much exposed. Her father stayed drunk and decided to start working with other men to build a dam or something and left the children but the son wanted to come. The girl started moving with her siblings to the original destination but stopped midway because she began her period, got scarrd turned back b/c she thought she was dying from a disease that other kids got but the fat woman explaind to her wat was happenin and she continued her journey. Shes bout 13 wen the story ends.