Sorceress...
Your metabolism decreases over time. If you do nothing at all, you will naturally gain weight as you get older. There is no need to speed up that process! Unless your DOCTOR advises you that your weight is unhealthy, the best thing you can do is to not make any changes at all to either your diet or your lifestyle...
As long as you are eating regular meals and getting regular exercise (5 or more times a week) then you are PERFECT, just as you are.
Note that "regular meals" doesn't necessarily mean that you eat breakfast, lunch and dinner. The healthiest people on the planet are those who just snack all day, eating like 10 or 20 mini-meals. Ironically, these people who snack all the time tend to take in fewer calories (each day) than if they were to eat 3 large meals a day. But if you eat regularly, even if it is the standard 3 meals a day, then you are fine...
I've dated a couple of full-grown women who weighed less than 90 pounds and they were both VERY healthy. Don't think of weight as a goal, think of fitness as a goal. And if you are confused on that, ask your doctor. Chances are, your doctor will tell you that there is nothing wrong with you...