I’ll just add that if you are bending all the way down to the Ab on the 3 hole (using a C harp) that means you must be using mostly the breath from the back of the throat technique. Which is great, because this is really important to master your bends.
Once you are doing this, and if you are looking for more control, I suggest trying to bend very slowly down to that note, by starting out with a very relaxed tongue/throat position, and a very relaxed breath, then ever so gradually increase your air flow while moving the breath back in your mouth, using your tongue again as a guide.
The desired result should sound like someone on a trombone, or a slide guitar. Then, when you have control of this, you should start breaking up the individual notes. Finally, those apps are great, there are more and more coming out now. I’ve just found another one i like called Blue Harmonica on itunes apps.