Best of luck, Traci! I'm sure it will be fine- I really think that if the tonal quality of your color (I.E. the yellow stuff) is what's bothering you, the ash toner should cancel that out. Your natural color is so light anyway, I'm surprised the color came out so yellowy. Another thing you could try is the Shimmer Lights shampoo from Clairol- it really helps with cancelling out brassiness, but only use once in a while. (I've had some clients turn their hair kind of grey with overuse).
Lol- whilst I've been writing to you, I've been coloring my own hair for our upcoming trip. Let me tell you- foiling ones own hair is
not fun.