@Christine M Tubbytelly: I do not think you can judge her body weight, unless you are her doctor. I was like her, probably with a smaller belly too at 6th month. You do not have to become overweight to be a healthy pregnant mom - in fact you must NOT become overweight, you must not gain too many kilos else you are in high risk of high blood pressure, high blood sugar etc.
As for whether women should cover their bellies or not, it's up to them to decide what they want to do. I do not think you would ask that same question if there was a photo of a pregnant woman at the beach gone for a swim.