Kimmy,
Steve said it best, acclimation is key. Medicine can only do so much, but spending a night or two at altitude before launch increases your probability of avoiding altitude sickness greatly, and in turn better chances of making the summit!
It was a good move to follow your gut, value the groups safety, and turn around. The mountain is going no where, and she'll be ready again when you are!
Did ya snag any cool photos along the journey?
Cheers! -Alex
