I'm 5'4", 155lbs, goal weight 135-140lbs, and currently have enough muscle to be <20% bf at that gw.
I am losing pure fat at a rate of 1lb/week, which I am fine with. Currently I eat 2200 calories/day on average, usually for 1 meal/day, sometimes including a coffee with cream during lunch. I work out 3-4x/week doing heavy lifts and sprints, and sometimes I do a three hour or so hike on the weekends. Seriously, you do not need to eat 1200 calories/day...in fact you should be eating more so as to not depress your metabolism.