Trying to trim down

Just joined MFP today. I have been dieting and exercising 2-3 times a week for about a month now. I have lost a half pound in that time. I work in an office where I am very mentally busy but I rarely do more than walk a little. I often am required to stay late and unfortunately cannot manage more than 2-3 times a week.

I had dropped down to around 1000 calories a day for a while and I am trying to wean my way back up to 1200 and maybe 1400 eventually.

My goal weight is 150lbs, which means dropping both fat and muscle.