Baby diaper

Hi everyone, i have a one year old girl and it has come my attention that people are her that are older are in the same size diaper. People keep saying she is in the wrong size but idk. She is in a size 6 Huggies she is 24 pounds. The size 4 were too tight and the size 5s fit good but she kept peeing though them. Her size six has been doing really well. Should I move her back down to a size 5 or stay in 6?