Yep agree with Jaxie.
MFP assumes you will eat exercise calories back so either stick with 1200 (or BMR) and eat your exercise calories back (to at least 1200)
Or plump for something higher (TDEE - 20%) but don't eat your exercise calories back.
Both should work, just what you prefer doing. I like a fixed amount, but some people find eating the exercise cals gives them more motivation to do the exercise.