I'd say there's a future for you, of course. You need to get work, but i'd start with doing web icons for people and iconographic illustration (posters maybe?), that sort of thing.

Identity (Logo) design is a packed market and is very difficult to do successfully. Effectively you have to be able to go to a business with the confidence to tell them your design will improve their bottom line, and you've to charge a lot of money for that. The reason being, most businesses don't just need a logo, they need an identity. That's colour scheme, font choices and brand guidelines. So if you're designing a logo, say you charge $300 (way too cheap for a logo), do you think that logo will make back the $300 your client spent on it?

Your design should make back more, it should raise their profile, bring in money. To do that you need to be in a position to tell businesses what they need in their given market. At 17 it's hard to imagine you being taken seriously enough or having enough experience with market places to do this correctly.

You should indeed be practicing, and doing anything you can. You need to be practicing Adobe Photoshop, Illustrator and Indesign. The first for photos, images, textures anything of a fixed resolution. Illustrator is a must know for logo design. Indesign is used for text layout on anything more text heavy than a poster.

You're not making a mistake at all, you're young enough to fulfill your aspirations quite early, but you have a lot to learn between now and being a "logo designer". If you can design logos, you should already be able to design a lot of other things.

Sorry this is a messy response, if you've any questions, shoot.