Assigned 1200 calories, eating more, still getting not eating enough message

Okay, so I am a really petite person trying to lose the last 10 lbs from a pregnancy 3 years ago. I am 4'11" and a stay at home mom... So I am not a nurse or waiter or such who walks 12 miles during work. So I marked myself as not very active with the intention of logging specific exercise in my diary as well. MFP gave me a 1200 calorie goal. The thing is, even if I log no exercise and go hundreds of calories over 1200, MFP gives me that message that I am not eating enough. Sometimes it will literally tell me my projected weight is an increase and then turn around and tell me it looks like I am not eating enough. I do not understand.