Yes, with that much intense activity, it IS possible you're not eating enough. Twelve hundred calories is usually the absolutely minimum any adult female should eat, and that's usually with little or no activity. In case you're not familiar with the ins and outs of eating "enough" ... here's how it works. Basically, you have a basal metabolism (BMR), which is how many calories you would burn if you did nothing but lie prone all day, and an active metabolism (AMR), which is how many calories you actually burn during the day, with all of your daily activities, exercise, etc. The guidelines that are currently recommended is that to lose weight you should eat less than your AMR but never less than your BMR. If you eat less than your BMR, you risk going into what's commonly called "starvation mode," where your body thinks there is a famine, and it cranks down your metabolism to conserve energy. Another thing that can happen is that your body will actually start to burn up it's own lean tissue for fuel RATHER THAN turn to your fat stores, because it considers fat stores more important to long-term survival. Losing muscle lowers your metabolism even further. In order to lose more weight you have to cut calories further, which launches you on a downward spiral.
If you go to http://www.jimkaras.com/loss_math01.cfm
, you can run your stats through a calculator which will give you an estimate of your caloric needs, assuming everything else is normal & average. This IS just an estimate, but it's a good place to start. If it tells you that you need a LOT more calories than you are currently consuming, you might want to increase them gradually over a period of weeks rather than all at once.
Other than that, you might want to consult a dietitian who specializes in weight loss or sports nutrition to make sure you're getting enough but not too much!