You should definitely try eating more.  I know this is much after the orignal post was posted, but how much do you weigh now?  The heavier you are, the more calories you need just to be awake, nevermind doing any kind of movement.  If you weigh 250 lbs (depending on your height of course, but I'm assuming you're not 6'2" or anything) you are DEFINITELY burning more than 1,500 calories.  Basically your body needs a minimum number of calories to be burning what you burn at your basal metabolic rate.  This means how many calories you would burn if you literally laid in bed all day and did not move.  If your body isn't getting those calories, it believes that you are starving and will start conserving energy (aka making fat) and eating away at your muscle for fuel to get through the day.  Since you want to burn fat, not muscle, you need to start eating more so your body does not think that you are in a famine!  Try going online and searching for a calculator that will tell you how many calories you burn in a day (it will ask you to enter your height, weight, and age usually).  Then you can get a very general idea of what you are burning.  Add in exercise and you will see the calories you expend every day.  I would not go much below 500 calories per day of that to lose weight.  To lose weight and keep it off you need to take it off SLOWLY.  Good luck!

You actually seem quite under weight.  When I put in your stats in the BMR calculator it says that you will burn 1385 calories just existing.  So what you can do to get an accurate assesment of how many calories you are actually burning would be to do a physical activity analysis.  That means writing down EVERYTHING you do and how many minutes you do it for, then finding an activity calculator online, putting in your weight and how many minutes you did what activity for, and it will tell you how many calories you burned, say, walking to the store, or standing for five minutes.  For sleeping, you use your calculated BMR/minute for however many minutes you slept for.  115 lbs seems very low for six feet tall to me.  I would add some calories to your diet (as well as adding more protein) and do some more strength training to add muscle.  With more muscle in your body, you will more likely see those abs you'd like because I really doubt you have a lot of fat on you.  Also, having more muscle will increase your metabolism and you will have a higher BMR.  Let me know how this goes and good luck!

Oh, did you mean you weight 215?  So you're trying to lose weight.  That would make more sense to me.  Let me know if that's correct.  Also, are you looking specifically at BMR calculators (those will measure JUST what calories you burn basically being alive).  You might be looking at a calculator that takes into account your daily physical activity. 

I would try raising your calories for a while and see if it helps.  I would also say as you are adding these calories add a higher percentage of protein and then add more strength training to your regimen.  This will build muscle and in turn kick up your metabolism, hopefully making it easier and faster for you to lose weight!  Good luck!