Hi there
You sound like just the perfect weight to me. I myself an 5'3 and when I weigh 150
pounds, no one thinks I weigh it either. I think it has something to do with
body type, and having a bit more muscle mass than others. I wouldn't worry so much about what the
BMI says. It's designed to be a general guideline to everybody, not really a specific meter to judge yourself by.
As long as you are eating healthy food, eating at least 3 meals a day (with 2-3 snacks), and doing a bit of exercise on a daily basis, I don't think you need to worry too much. If you wanted to trim up a little bit more, you could always take these suggestions into consideration, although a lot of people can get by looking quite healthy without exercising that much. "Exercise" by the way, doesn't have to mean strenuous hard activity-it can be as simple as walking 20 minutes a day or taking up volleyball or
yoga.
Hope this helps you out a bit