I definitely agree about the parental support and approval at your age. You must have it. You also need to concentrate on your schooling and do your best at that. Most people who want to be models don't make it to the top in that industry. It is a lofty goal and worthy to aspire to such a thing, but I would be prepared to be successful at the other things in life that you might choose to do - have a boyfriend, get married, raise a family, etc. Remember that I am saying, if you choose to do those things. Being a model is not necessarily something that you will do for the rest of your life. A big part of being a model is how you look and carry yourself. Everyone changes in their shape and appearance over time. You may not be marketable as a model for all of your life, depending on what the employers are looking for in the models that they hire.
You may find some local agencies in your area that put out advertising for clothing or other things that you might investigate how to become a model for them. Doing this type of thing might be a supplement to an income that you already have in the future or even now.
Having a portfolio is important. The advice in the post above is great concerning that. I don't know that I agree that it is a sick world overall concerning that, but I do agree that you have to be very careful and look after your own interests and protect yourself, not only in the physical sense, but in the monetary sense as well. It's best to have someone who you know that you can trust to do any negotiating for you as far as fees paid and anything concerning a contract that you might sign.
You also might like to check out the information on the following sites. What you find may be helpful to you. I hope that it is.
What does it take to become a model How to become a model How to become a Model with Wolf's Models Guide HOW TO BECOME A MODEL, Fashion Model, Teen Model or Male Model MODELING AGENCY - HOW TO BECOME A MODEL