Take MFP calorie goal with a 'grain of salt'

My calorie goal has been at 1200, and I have been reading post after post about people losing more weight when they increased their calorie goals. I talked to my brother, who is a trainer, & he said 1200 is way too low, unless you are 125 pounds (which I am no where near). I found a site that gives a more accurate calorie goal, and if you scroll down it gives lots of details on calories, fitness, etc. http://www.freedieting.com/tools/calorie_calculator.htm

I just manually increased my calorie goal to 1500, but even that may be a little low. I was feeling very sluggish the other day & I really think it was because 1200 calories was slowing my metabolism.