MFP and BMR don't add up?

Hello-
I signed up for MFP a long time ago, but just started seriously using it several weeks ago. I lost 8 pounds in the first few weeks, but in the last three have not lost more than half a pound. I'm super frustrated, so I started doing some research to see if I could change anything.

According to MFP, when I plug in my current weight, goals, etc, I have a daily caloric allowance of 1200 calories.
However, when I plug my stats into this: http://scoobysworkshop.com/calorie-calculator/ (which someone suggested elsewhere on this forum), it says I need more like 1400 calories, and that going down to even 1300 could be dangerous. Am I not eating enough?

I am 5'1" and currently weight 144 lbs. I would love to get down to 130, if not 125.
Thanks!