Having an "amazing portfolio" is one thing. Being able to produce amazing results every time out for every client is totally another. What type of work are you hoping to do? Pets, kids, families, seniors, fashion? Weddings??? (Please say you aren't looking for wedding work as an easy cash cow.) A better angle might be to submit some of your work to the various stock agencies and see how that goes. You'd probably have to have a parent do it, though, until you are of age.
Also there is the matter of equipment. Although your Fuji is a good camera and does have manual controls, its smaller sensor will suffer under some situations when compared to a dSLR. Mainly producing shallow DoF and high ISO performance. Those are limitations that will be hard to overcome if shooting people is what you want to do.
You are correct that people are unlikely to take a teenager seriously. As a 16YO, you also have to consider the legal aspects of having a business, particularly liability and contract. What happens if someone trips over your tripod and breaks a leg and sues? As a minor, your parents might be liable for damages. Your attorney should advise you about that, as well as the tax situation.
Finally there is the matter of undercutting the professionals. Either you are good enough to get paid for photography, or you are not. There are a lot of new camera owners who are getting into the business as well. (Many will have "better" cameras than you, BTW. Skill is another matter, not too many of them will have much...) These newcomers, as well as the established pros are your competition. How do you plan to get clients? Do you have a marketing strategy and business plan? How much do you have to charge to make a profit and stay viable? Doing $200 weddings ain't going to cut it, I'm afraid, unless you can do 10 every week and spend minimal time in post.
A first step might be to get in touch with the Small Business Administration or it's equivalent in your area. They can help you decide what a good plan would be to get started. It is possible to be successful in a new photography business, but frankly, with the current economy and large crop of wannabes who work for almost nothing, it is unlikely. Good luck.