Over 35 forum is recommended. Weight lifting is more fun than cardio, and takes less time (about 3 hours a week) - plus you can eat more and still lose fat. Your mass is not what matters - it is your body fat percentage. 4 lbs of fat occupies the same volume as 1 lb of muscle. And, for women, getting that nasty manly look you see on female bodybuilders is nearly impossible. It won't happen naturally (ie they take steroids, etc). And they cover themselves in awful PROTAN too.
If you are making progress towards your goal, don't change anything (sounds like you are doing great - congratulations so far, keep up the good work).
However, for a lot of people their basal metabolic rate (BMR) is too low for diet and cardio to help enough. You can increase your BMR by increasing your lean body mass (muscle burns calories just sitting there, while fat is "inert"). So for anyone who has tried the diet and cardio angle of attack and not obtained results, there are other ways to get fit. Different bodies need to be prodded differently to let go of that extra fat - there is no one size fits all solution.