Somewhat alarmed about weight gain...

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Ladies, I am hungry ALL THE TIME. The second semester has introduced me to intense hunger pains.  I am a FTM in my second trimester.
The problem is, I was a petite 125 to begin with, and 131 by week 13.  In my second trimester, week 15, I am averaging an increase in weight of only 0.5 pounds. I read that the average is 1-2 pounds.  I am eating all day.  I eat green smoothies, fried chicken, ice cream, pie, salmon, sweet potato... and yet I am losing weight in my shoulders, as evidenced by me wearing a pre-pregnancy off-the-shoulder dress and the sleeves are simply looser than they were.
My husband is worried not that I will be too big to fit into my old clothes after pregnancy, but that I will be too small! My stomach and breasts are getting rounder and larger, and my thighs are slightly larger (or maybe less toned - the first trimester knocked me out) but other places are shrinking!
Has anyone else experienced this?