What do my BMI results show me? do i have a high metabolism, am i under weight? Thanks for answering :)?

Not sure about the metabolism rate, but it sounds like your results are just about right for a 16 year old. Those are pretty much the same readings I had during high school ( I was 5'6" at 16), and from my BMI, I was always on the line between healthy and underweight. If you were 20, you'd definitely be considered underweight, but I'd say you're healthy for your age and height.