My Fitness Pal tells me 1600 a day, not including exercise cals. I average lower than that, probably around 1300-1500 net. Today I deliberately had more as I've been feeling down and tired. My target was 2100 after exercise, I ate around 1950.
I get 1700. I used to get 1800 like you, but as your weight goes down, so does your calorie intake.
Go on MFP and go to tools. Check out your BMR (basal metabolic rate). It will tell you how many calories your body is burning just to stay awake. I bet it's quite a big amount of cals? If you eat less than that you will loose weight, so it makes 1800 seem alot more acceptable.
I'm on 1240 cals because that's what MFP tells me is the right amount to lose a pound a week. However, I am almost 50 pounds lighter than I was at the start of my journey and near the 'normal' range so it's bound to be less than it was at the beginning of the year.