I think the idea about volunteering is a great idea - at least to give you a hand on experience for how they are and the kind of work they take.
I'd like to share my thoughts because I loved ferrets all through my teen years but I did not get one (*coughcough*3*coughcough*) until I was an adult.
Things change quickly.
The homeschooling is probably a better scenario than most teenagers wanting a ferret because you will be at home versus away at school. But please think about the ferrets lifespan. It seems the bottom end is 6 years with people having them to ten years and further - depending on a variety of factors. The advancements in dietary knowledge will only extend that, as well. You have the time now, and I'm sure it's a little crappy for you that so many people are telling you to wait but please have an open mind. When I was 13 I was kind of "dorky" and spent a lot of time at home... then boom at 14 boys boys boys! I wasn't wild by any means but a lot more of my time was spent out and about hanging out with friends and boyfriends. This is when you're discovering who you are. Then you'll be 16 in 3 years and wanting to drive. Once you get your freedom you'll most likely be out more - especially since you were home schooled. 2 years after that is college. What are your plans for that? Are you going to a local school or moving away? At that point, if you aren't living at home, you need to think about a landlord that will allow ferrets (unless the stigma changes, it doesn't look good!). A dorm is out of the question with a ferret. Will your parents give the ferret the love and attention it needs if you choose not to take it to college with you? I know it seems so far away NOW, but that's only 5 years from your age now.
Then you have around 4 years of school, assuming you're going for a traditional degree in the USA. During that time you're going to be wanting to hang out, go to parties, date, do school work and be at class, possibly have a job by then as well. At that time you'll have an elderly ferret that may need a lot of medical care. Will you be able to provide that?
If you don't go to college what are the arrangements for who is responsible for the care of the pet after you reach adult hood. Apartments are expensive, bills are expensive. Ferrets, like any pets, have the tendency to get in trouble. You may have unexpected vet bills.
Those ideas aside, I don't think when people say you'll lose interest that they really mean you won't care anymore - that's definitely not the case. But a lot more rests on how much time you'll have and BE ABLE to devote to the care of the ferret. In my opinion, only ferrets need more attention than pairs+ (not that pairs+ don't need attention) because they have eachother to care for.
All of your best intentions aside, a ferret is a BIG commitment. How will your parents handle it if potty training doesn't go as planned, or if the ferret becomes sick, eats something it shouldnt or gets an obstruction? Have you researched the medical complications that can happen with ferrets and decided on what you'll be able to provide if they happen. More importantly, have you discussed these possibilities with your parents? It's sad to say, but a lot of people feel more able to justify a medical treatment plan for something like a dog or a cat versus a small animal. What discussions have you had with your parents about this?
I'm not at all trying to be overwhelming to you, but these are all important things to consider. I waited to get a ferret. I had a hamsters when I was young and then got a dog around 14 (my mother and stepfather ended up keeping him when I moved out because I couldn't afford it). I would not have been able to feed the ferrets an acceptable diet if I had gotten them at a younger age (try justifying 50$+ dollars a month to your parents for simply food and other necessities. Granted, I have 5 animals eating the same food).
I got the first two ferrets 3 years ago, and the third one 1 year ago. I was married but still in college. Working a part time job, being a full time student and being in a serious relationship was a serious drain on my time BEFORE getting ferrets. Afterwards it was more time devoted to them as well. I went out less (which for my lifestyle is fine). I limited vacations and trips to ones I could either take the ferrets with me (visits to family) or I had to make sure that I did not take ones longer than a weekend because I didn't have people I could trust to watch them.
Overall I am so glad I waited to get ferrets until I was an adult. I have the income to get them great food, more toys than they ever care about, the best cage I felt existed, and if one of them (knock on wood) gets hurt, then I have the means to make a decision based on the animal's prognosis rather than my checkbook. I think if you wait you'll enjoy them much more as an adult rather than as a teenager.
As a different idea, if your parents are open to small animals why not rats? Rats like 3ish years (I'm not an expert I could be wrong, do your own research) and I have read they have adorable personalities and are a super fun pet. Given their life span, it seems it might fit your age a little better to have something that will be less of a commitment in the longrun.
If none of us manage to sway you - at least try to adopt an older ferret who perhaps is potty trained already, who may pass the bridge by the time you're starting your adult life and college.
<message edited by Seelen on Thursday, October 08, 2015 4:44 PM>