Your BMI is based on your height and weight. We have a handy dandy BMI calculator right here at 3FC: BMI Calculator
When you plug in your height and weight, you'll get a number. The chart under the calculator will tell you what category you're in ... normal, overweight, obese etc. Any BMI between 18 and 24 is considered normal.
I just went and put your height and weight in that you have in your stats. You currently have a BMI of 25.8, which puts you in the overweight category by just a little bit. Losing just five pounds, down to 145, would give you a normal BMI. Very do-able!