projecting my feelings?

my husband and I have been trying to have a baby for 6 years in that time two of my younger sisters have had kids. the oldest of my two younger sisters has a boy who is almost three and since he was about 6 months my husband and I have taken him a couple weekend's a month. my sister isn't a good mom and I worry about my nephew. Am I just questioning her parenting because I would do it differently or is it something we need to worry about. everyone I know agrees that she isn't doing a good job and that he needs to be placed somewhere else but I feel like I'm not doing enough to help him. could I be doing more to help him