She's SOOOO SMALL!!!!

I know it's bad for one of my first posts to be on this topic, but I am so tired of being told how small my baby is by complete strangers!
"What are you feeding her? Maybe you should start cereal now (forget what the ped says) to get some fat on her!"
"Are you breastfeeding?" (Yes.) "Maybe you don't have enough milk." (WHAT???)
"Wow, she's TINY, was she a Preemie?"
So if I say she's not a Preemie, it means I'm doing something wrong to make her small? Actually, she was born on her due date, 6lbs 8oz at birth, but she's always been really long with a small head (5th percentile) so she does look petite compared to other babies. The pediatrician says she's fine, she's growing at a normal rate, and she's a healthy, happy baby.

I'm sure moms with larger babies get even more insensitive comments, but it just drives me crazy sometimes!