It sounds like your son is a good eater. You may not need to bother with bottles if he is already taking liquids form a sippy cup. Introducing the bottle now might just confuse and complicate the process. If he is doing well with the sippy, he will eventually move right to a cup. Breast to sippy to cup works great, no need for bottles.
Weaning at this point depends on how many feedings he is taking. The old saying for weaning goes, Don't offer and don't refuse. If he is busy with an activity, he may "forget" to nurse, which is how a lot of kids start to wean themselves. All you have to do is not remind him that it is a nursing time, and make sure he is eating enough at his meals. Also, when the time comes, eating parsley and sage helps to naturally diminish your milk supply, to lessen engorgement and discomfort for you.
Good luck!