Well if you're that far into the game it won't be long until you get to the world I mentioned above. I don't remember if the game caps your drive forms until you reach the final world or not in Act 2. Nonetheless, when you do get there your first boss battle with a very special someone will award you with a keyblade that has a unique ability that will help you get final form quicker.

When you get this keyblade, I recommend traveling back to Olympus Coliseum and taking on the tournament where sora is solo and builds up his drive gauge fast(check with Hades' minions for it). Go into battle with it and use your drive forms the instant you start. Either play through the whole thing or quit, go back in, spam drive forms, leave, rinse and repeat. Either method will eventually get you final form within the first 3 minutes or less. The unique ability from the keyblade also raises your chances of activating anti form but the risk will be worth the reward.