hey there, i thought i could help you here, you dont need to take the 500 away from your BMR, you need to take it away from your burn figure, which is your BMRx1.2 which in your case is 1902, so you need to take 500 from that which is 1402 which is the amount of calories you need to eat.
hth
If you need help with calorie counting you can visit the food focus website.