Baby growth spurt?!

I have to get ultrasounds every 4 weeks due to being high risk. Today my little drama queen at 24 weeks, 2 days weighed 2 lbs 10 oz!!! That's double what was expected. I eat healthy, I haven't gained an excess in weight, I don't have diabetes, WHY is she so big?? Haha my husband was a 9 lb baby but I'm 5'1 and pre-pregnancy weight was 115. I am little, I cannot be having a gigantic baby! Anyone else in the same boat?!