I'm extremely pale as well and when I wear the palest foundation I can find in most shops I look ridiculous and like a completely different person (to me, anyway). I'm basically orange, and I have to blend it down my neck and into my chest so it doesn't look obvious. If you're normally using a darker foundation, then using a paler one, even if it matches your skin. will still make you look different.
What foundation was it? Cause I'm wanting one that's pale enough to keep me looking like me. The only one I've ever found that was pale enough and not bank-breaking is Loreal Infallible, but that's too liquidy for my liking