Hi Lorin

7kg is a little low. Weight gain depends a lot on what your weight was before you got pregnant. If you were underweight then you can expect to gain more weight than I you were overweight. Below is a very rough guide to how much weight you can expect to gain.

Baby 3.5kg
Amniotic Fluid 1kg
Placenta 700g
Breast Tissue 1kg
Blood Volume 1.5kg
Uterine Muscle 1kg
Water 2kg
Maternal body fat 4kg
Total 14.7kg

Don’t worry about your weight gain. It is far more important that you have a good well balanced diet.