I know how puppyitis can really get to you. I get bouts of it all the time, but have to resist because I know that it would be too much for me in many ways.
I hate to be a downer, but I think your hands are over-the-top full, as it is with Ruckus and Lyn. If I had the issues you're having with your dogs, there is no way I would get another dog. It's just too much work, you would be spread too thin. You truly might wind up with a puppy that gets screwed up. It's just too much. And that's not even to mention the rabbits you have to care for.
You're young, right? You have time in your future to get a Westie. In the meantime, I would recommend you put all you've got into the two dogs you've got...training, working on issues, giving them the attention they need.
Sorry....It's probably not what you want to hear.