Hate telling people how much my daughter weighs

I'm naturally a thin person and I always have been, just like my mom, and it seems my daughter is too. She just had her 9 month check up today and is only 16lbs which is the 5th percentile and her height is the 55th percentile. Her Dr isn't concerned and neither am I. In fact I love that she is petite. She was born on her due date but was only 6lb 4oz. But she doubled her birth weight by 4 months and is on track to tripling it by a year like she should, she is just small. When I was pregnant my mother-in-law warned me that she likes her babies chunky. This pissed me off because I always figured my daughter wouldn't be and I didn't like her attitude about it even then. She constantly questioned my husband and I about how much weight I was gaining because I guess it was never enough for her (I gained 40lbs while pregnant) Another baby was born on my husbands side of the family a month after my daughter was born and that baby is extremely chunky and my daughter is always getting compared to her. Every time we get together with them my daughters weight is questioned. I hate feeling like they're not happy with my daughters size and like they think the other baby is better. I was told I was skinny my entire life and I'm going to be really defensive of anyone making my daughter feel like she's not good enough and like there's something wrong with her because she's thin. I want her to love herself and not feel self conscious about her size. So my question is.. how can I tell people (mainly my mil) that I don't want to talk about my daughters weight? I don't want my daughters weight to be judged. What can I say when they ask how much she weighs? If I say I don't want to talk about it that might seem like there's actually a problem with her weight.. any suggestions?

-I just want to add that my daughter does look chunky- she has rolls! Just a small frame. She's a breast fed baby so she's also naturally smaller than most formula fed babies