Lets hit fit first, if you can't get the call in between your teeth try a youth model. The call should sit in between your teeth as far forward as possible. This does two things: #1 makes the call not move in your mouth when you call. #2 Makes the call sit at an angle in your mouth, back up against the roof of your mouth and the front down because of your teeth. With the call sitting this way you will get the best seal from your tape. This makes your calling more consistent, the call isn't moving and all the air is going to calling. One other thing, if the frame of the call fits between the teeth OK and the tape is too much, trim the tape. But very little at a time. If you trim too much the call will be worse than it is now.
Now the calling part, if you push the call to the back you will be using a part of the tongue that will make it hard to do some of the fine calling. Light putts and purrs, the tongue is to wide and not as nimble as closer to the tip. Also you are balling up the tongue and blocking the air from coming out, not to mention inhibiting the vibration of the reeds. Both of these things cause your sound to not be as good as you want them to be. Hope this helps Bob H in NH.
Gselkhunter