If you're pessimistic & assume you've been friend-zoned, then it's already over, and that's just all it will ever be...

Instead, try taking the initiative, and the next time you see her, say, simply, "I was thinking some more about how bad it was when you asked that guy out and he turned you down, and how unfair that was, since you are an amazingly special girl and I have no idea why anyone would possibly turn you down... Frankly, I'd be honored to ask you out myself..."

And see what happens...

At the worst, she'll say "I don't see you that way, sorry"... At best, either she already likes you, or wouldn't want to disappoint you the same way she got disappointed by the guy she liked, and will say "Sure, why not"...

Either way, it's worth it to try, instead of assuming you're nothing but a friend, and putting yourself in that position just by assuming so...