1200 calories is pretty low for your current height and weight. Your not going to want to go below 1500-1600 especially if your working out

When your filling your body with healthy foods you'd be amazed at how hard it is to reach that number sometimes :P
I started calorie counting and keeping a 1500-1800 range but didn't have much success losing. I upped my calories to 1800 as my minimum and now i'm losing pretty consistently
Most people are surprised at how many calories we actually consume when we're not calorie counting. I think i was eating around 3000-4000 a day before I started watching portions, but I was positive I wasen't going above 2000 or so.
So play around with the amount and try and figure out what is best for you. Give it a few weeks and see if your seeing results