I'm a Gestational Carrier (surrogate)

I stumbled across this app while searching for an app that would help me count calories so that I can have a healthy pregnancy. This is my 7th pregnancy, my 4th and final time as a surrogate because I will also be having a 4th c-section and my 1st time carrying TWINS!!!

I'm 20 weeks now and feel like I'm already way to big. I'm not sure how this can be when I've only gained 3 pounds. According to the research I've done even though I am considered obese I'm suppose to gain 35-45 pounds. I'm only 5' 4". I feel like that is way too much additional weight.

Has anyone else out only gained very little while carrying twins?