I'm so worried about my baby.

I'm really worried about my little girl. 
I wasn't until I began getting non stop comments on my daughter's weight. She was born 06-24-16 (she's 5 months) & weighs 18.14 lbs (95th percentile). I suffer from hashimotos (hypothyroidism) and all the women in my extended family get it in their child bearing years. But one of my cousins just got it at age 9! I worry because at her 4 month checkup she was 17.8 lbs & she was only in the 78th percentile. That's a big jump in only a few weeks! She's a wonderful baby and she makes me so happy and brings joy to everyone she meets but I am SO worried!!! Do I have to worry about hypothyroidism with her? Is she considered overweight?
Below is a pic of her. She really is my shining light ❤️❤️❤️