Weight!!!!!

Amber • I am not a first time Mom because I have a beautiful step daughter but this is my first pregnancy and with twin boys 😍
I am currently pregnant 20wks with twin baby boys first pregnancy and really wondering how my belly keeps growing and I keep thinking I have gained a lot of weight only too go to my doctor appointments and only have gained 5Ibs and I'm 5months pregnant please help explain this too me ❗️❗️❗️