Not 500 extra calories. More like 200 and when you hit your 3rd trimester it goes up another 250. Don't worry about gaining a lot of weight some mommas put on 40 pounds and lose all of it after baby is here!
If your bmi is within normal range then the healthy amount of weight to gain is between 25 and 30 pound. Just continue to eat healthy keep up with walking etc, you only need an extra 500 calories a day when pregnant.