Trying this again!

HELLO People! I did MFP about a yera ago and managed to get down to the weight I wanted. I was eating 1200 calories a day. However, I fell of the wagon for a little while and gained it all back and then some.
Now I have read in places that 1200 calories is too little. I set mine at 1400 now, however I am not really sure if that is right.
If MFP says 1200, but that is too few and will cause my metabolism to slow down, then how do I know what I shoudl set it at? I am 5 2" and weigh 130. I am trying to lose 15 lbs. Any advice would be really appreciated! Also it would be cool to have someone to set up a buddy system with and share success etc. Thanks !