The gear you already have is perfect for being an "Uncle Bob" -- that guy with the "serious" camera equipment who show up to all the weddings. And being an Uncle Bob can be a lot of fun, and you can even get some good shots out of it. Especially if you forget about the classic must-have shots and instead focus on the types of shots that the hired photographer isn't going to be bothering with or isn't in a position to get.
So, the next time a friend or relative invites you to a wedding, do exactly that, have some fun, and get an idea for what the hired photographer is doing.
If you really had a lot of fun and you got a handful of good shots and you still think that's something you want to do for a living, contact some well-established local wedding photographers and convince one of them to hire you as a second shooter.
At that point, you're off and running.
You might notice that my post is almost entirely devoid of gear advice. That's because, even though wedding photography demands some of the most expensive gear setups in all of photography (basically, low-light high-reliability photojournalism), the gear is actually pretty far down on the list of what you need to be a successful wedding photographer.