Quite frankly, I'm surprised the Dr said "it's quite a painful surgery"!!!!!! This is a VERY routine surgery, that doesn't even take 30 minutes to do for any ENT surgeon.
Young patients have been "bouncing off the walls" within a day or two ofter the surgery, of course there are always the exceptions to the rule.
My sister had this done when she was in her 20's............she played in a Volley Ball game within 48hrs, and didn't show any signs of the surgery!
I support the surgery. This will eliminate all kinds of things later in your daughter's life. It's better to get it done now while she's so young.
If you're concerned........get a second opinion.Perhaps you dn't have the "right" Dr. for your daughter for him to sound so .........well so discouraging about it.
Unless she has complications.......she won't be missing 7-10 days of anything :o)
~N.