Because of my age and my height MFP puts me at 1400 calories to maintain. As I am not supposed to eat less than 1200 it says I should lose 0.4 lbs per week and 2lbs by October 23rd. This really is not much so any cheating I do or mistakes I make will soon eat up that 0.4lb loss. I suppose with you it depends on your age and height.

If I want to eat more or better still, lose more, I need to exercise more. That way I burn more calories. It is really all attention to detail. Weighing everything that goes in your mouth. Also Fitbit is not necessarily accurate so I don't eat back all my exercise calories.

Weight loss gets harder the older we get. I don't know your age but just telling you my side of things.

I don't really know why there is a difference between the two unless you have them set up differently. E.g. sedentary or slightly active. They are both only guesstimates really. I usually go with MFP for my calories.

I am sure someone else may have a more scientific answer for you. I just know I have to be very careful or I don't lose anything.

I found it fairly ease, and quick, to lose the first 5-7%. Since then it has been very slow in moving the scale. My guess, for myself, is that to drop another 10 or so pounds I'd need to cut back to a level below which I am comfortable. what I am looking for is a level that both lets me continue to lose a couple of pounds a month until I reach my goal but that is also a level I can live with for the next 20 or so years. From what I have read, bouncing up and down is much worse that sitting on a plateau even if that plateau is higher than I'd like. Looks to me like you were losing 2# per month then your body got used to the new you and slowed down. However since the scale is still moving, however slowly it might seem, things look to be going in the right direction. If you had lost the 27 pounds then gained 4-5 back since July I might be concerned.