Just make sure you are taking a good prenatal and eat good meals with snacks in between. If ur doctor isn't worried and the baby is growing good I wouldn't stress. Good luck.
Well if your dr isn't concerned I wouldn't worry too much. As long as the baby is growing fine. Ask him/her if he recommends any changes in diet or anything additional you can do safely to gain weight. I wouldn't go out and just eat junk food the entire time just to see the numbers go up. My aunt only gained 12, and 16 pounds with both her pregnancies. I gained 35+ with both of mine.
I had a appointment yesterday and I'm under weight. I'm 5'10 and weight 133 pounds and 3 of them I just gained this month alone.
I wouldn't worry too much about weight gain if your dr is ok with what you're gaining. All pregnancies affect your body, age can play a factor, but just because you're older doesn't mean for certain that it will affect you in a negative way. Many older women have completely normal pregnancies.