Polar F6 Female HRM Question

Ok so I finally tanked and bought an F6 HRM last month! I absolutely LOVE it and wear it whenever I work out. It's so nice to finally see how different the machines at the gym are from actual burned calories. I have a question about daily burned calories though...

I am 21, about 5'6'', and weigh approximately 118-120;bs. I've always had a high metabolism, mainly because I've been in competitive sports my entire life. I'm not looking to lose weight, but maintain or even gain a few pounds. Just as a side note, I eat a lot of food - more so than my fiancee .

Yesterday I was curious about how many calories I actually burn in a day (just to see what it would be - i've been dizzy for a few weeks and was wondering if I'm not eating enough from working out..i usually eat around 2000 cals a day and have more than enough water). I put on my HRM when I woke up at 7:30 and set it up - it did the Own Zone thing all day. It was a mostly relaxing day, but I did work out for a half hour - burned 300 cals on an elliptical. What I'm curious about is that I know that for your organs to function normally, you need approximately 1200-1300 cals a day. What I was surprised to see when I went to bed at 11pm is that the HRM only posted in 1500 cals burned. From this site, and mypyramid.gov it's recommended that I eat 1700 cals and 2200 cals, respectively.

So, basically...does the HRM track EXTRA cals burned, meaning, did I burn 1300+1500 =2800 cals yesterday, or did I really only burn 1500? My resting heart rate is about 70bpm, which is normal for an active person my age. I dunno, I just feel that number should have been higher...any thoughts?