Much of the following was a reply to a similar question from a pitcher. It pretty much holds for you as well.
Increased velocity will come through improving your mechanics, getting stronger and growing. You have no control over the latter.
Getting stronger will be best accomplished by a baseball oriented strength training program. Perhaps the best way to do this would be to find a good strength training facility that has a program designed around baseball. Once you have trained there for a while, you can probably then proceed on your own by following the regimen you were taught.
Be sure to keep your protein intake up since you are working out hard. You don't need supplements, just eat lots of protein containing foods.
Keep the rotator cuff balanced by doing the Jobe elastic band exercises. This is very important.
Running and agility training will help as well. The agility training should help a great a deal toward faster footwork.
Improving your mechanics will probably require working with a good catching coach. You will see quicker results from improving your footwork and your throwing mechanics than you will from getting stronger.
Now at catcher, your footwork is
extremely important. Extremely. You need not only the proper footwork, but
very quick feet. Thus the recommendation on agility training.
Consistency will come from consistent footwork and consistent mechanics.
You might try sending a PM to Catching Coach. I think he is up in the northeast. Seems to be very knowledgable on catching.
"Show me a guy who won't pitch inside and I'll show you a loser" Sandy Koufax