Gelsomina,
There is no such thing as over training IMO. Keep doing what you're doing.
1) The more you're out there, the more you'll find out about yourself and your gear. It gives you an opportunity to try different clothing, packs, foods, boots, etc.
2) Over training means you'll be smiling all the way up Whitney and all the way down. Why just be "good enough"?
3) Depending on the time of year, I'm up in the mountains at least monthly if not weekly. There was a point that I was doing Skyline and Cactus to the Clouds at San Jacinto almost every week and was comfortable during and after the hike, but never did I think nor did I feel like I could skip up and down Whitney.
It looks like you'll make it up to the summit on your date, weather and altitude issues aside. I say keep training (harder) so you can do it in style, having fun, and yacking with your friends the whole way.
