Anna -
I'm also a calorie counter. What you want to do is find your BMR. (here's a good one:
http://walking.about.com/cs/calories/l/blcalcalc.htm) For example, I'm 5'2" - #186 - and I do light activity (generally 1-3 xs a week) so mine is 1900-2200 calories/ day. In order for me to lose weight I have to eat less then that. You should NEVER go under 1200 calories a day - your body needs AT LEAST that much! I keep my range between 1200-1500 a day.
#1=3500 calories. So to lose #1 a week you would need to burn 3500 more calories then you ate. My goal is to have a "Calorie Deficit" (burned more then ate) of 750-800 calories a day which is about #1.5 - #1.6 a week.
Of course there are always other factors that play in, sodium, hormones etc.. but this is a good starting place

There is a calorie COunters forum on here too which those girls know a TON more then me!
