Are you actually in the wedding? If you are then I can understand but if you aren't...absolutely no one is going to be looking at you. And out of everything your friend is going to remember your hair won't be anywhere near the top of the list.
My best friend got married a few years ago and she doesn't even remember me kissing another friends girlfriend during the pre-dinner MC shenanigans. In front of her entire family. And she's the one that started it! Long story short that tapping the glass to make the bride and groom kiss thing got waaaaaaay out of hand...but that should give you some perspective on how little your hair really matters.
It's really great that you want to do this for your friend but if she has specifically told you not to worry about it. Don't worry about it.She won't be. Trust me. Your hair seems like a big deal to you because it's your hair. Your friend has bigger fish to fry. She's getting freakin married. Do you know how many other things she has to stress about that are far more integral to her day than your hair? So much crap that after watching my friends worry and stress about all the insane details that are involved in having a single day party go smoothly I refuse to ever get married in such a fashion.
All that said, you still want to be a good friend and you asked for advice about your hair...
How short is your hair? Is it so short you can't clip sections back from your face? If you can, just buy some pretty clips and arrange them and your hair in a tasteful manner and just use aloe to smooth out the frizzies.
Perhaps if you post some pictures or give us a better description of your hair we can give you better ideas.