BMR, TDEE and weight loss

Shari325

Help me understand how these numbers apply to me.
MFP has set my daily calorie limit at 1600.
I am truly sedentary due to physical limitations. I am unable to do very much, including walking.
According to Scooby's calculators my BMR is 2100 and my TDEE is 2490. TDEE minus 20% is 1990.

I have been eating between 1400 and 1600 calories a day and I am losing on average 4# a week for the last six weeks.

If a pound of fat is 3500 calories, a loss of 4# a week means a 14,000 calorie deficit per week, or 2000 calories per day.
Does that mean my TDEE is actually closer to 3600 per day? And, if I wanted to slow my weight loss to 2# a week I would need to increase my calories to closer to 2600 per day?

I have a scale that calculates % body fat & % muscle. Although I know these are not overly accurate, it consistently shows a decrease in % body fat (7% so far) and a slight increase in muscle mass (1%). As long as this trend continues, I am not going to increase my calories that much because I still have over 100# to lose. I assume when I have less body fat to burn, I will need to consume more calories to prevent muscle catabolization.