I went from 196 pounds before I got pregnant with my daughter to 163 the day I checked in to deliver.
My best friend actually lost weight her entire 2nd pregnancy. She is plus size and had gestational diabetes. Her Dr was never concerned about her weight. Some women gain little to nothing.
The cramping is from your uterus expanding. It continues until you're done growing.And you don't really need to gain weight yet. If you had any fat reserves, those will get used first. But when you get to 20 weeks you should start gaining a little more weight.
Im not sure about the cramping but as long as theres no bleeding associated with it that's a good sign..as far as only gaining one pound, well i lost11 pounds this pregnancy in the beginning. It want till about 5 months that i started putting on weight and i was average size to begin with. It worried me too but as long as you are eating enough your baby will take what it needs from your resereves. I know its really hard when you feel sick to even think about eating. My nausea and food aversions were so bad the first months i was in bed almost all day.it was rare to even think of anything i wanted to eat.