I took them back!
I heard on Friday that the bride herself wasn't going to be wearing her wedding dress to the party (they married in Vegas 2 weeks ago) so I decided the flowers for my hair would be a bit over the top for me, a mere guest! I was also not completely comfortable with the way they stuck out from my head - I think if I decide to go for head flowers in the future I will look for something lower profile lol!
So back to the shop they went!
Thanks everyone for the advice!