Michelle, congratulations for winning your class at the Nationals the bad part is that you are now hopelessly hooked
My advice to you would be that unless you go to a lot of matches where you shoot hunter class matches you may want to get a Standard rifle class as well. See, even good shots like Cathy or Agustin shoot two rifles, the potential for you to get a better score with a standard rifle is greater than with a hunter because you get a better fitting stock, a lighter trigger, etc. in other words easier to shoot.
The time you are spending practicing will help but only if you are applying and working on the right techniques. Experiment with different holds and try to use bone support rather than muscles. Watch pictures of people that are winning and try to imitate the way they hold their rifles, this will cut down on the time that is going to take for you to reach Master class.
It is very important that you work on the mental aspect of the sport, read books by Lanny Basham like With Winning In Mind and The New Position Rifle Shooting by Bill Pullum & Frank Hanenkrat that without a doubt is the best book about shooting that I have ever read.
Good luck in the future. Tony Tello