Sister in law has no kids and keeps giving me unsolicited parenting advice.Am I wrong with snapping?

I have a 9 month old baby girl and my sister in law is a medical student. She doesn't comment much but sometimes she points out things about my baby's development that hurt my feelings. Like she will say "she's coming to the age where she can start crawling soon!" And it makes me feel guilty that my daughter isn't crawling or hitting milestones. Today, I shared a video of my baby on a walker and she said it was cute and then shared that she learned while on her pediatrics rotation that the pediatricians didn't recommend walkers and sent me a link that said walkers slow baby milestones. I ended up getting frustrated and told her to leave the parenting to me and mind her own business and if I had any questions, I'd ask her. My husband said that was rude of me. Am I wrong?