Names are tricky. The name my mother loved for me, I grew up hating. If it's really a bad fit (mine was), you could change it, or keep it and let her find her own name when she's ready. (I know all of this might be way too hippie for many out there, but let me just say that this worked for me!) One of my dearest friend's found her true name in first grade...and she's in her 60's with that same true name, so one never knows...
I had to go through the court system to have my name legally changed, and it's likely you will need to as well, esp. if there's a social security number involved. This will involve going down to the SS office with the appropriate paperwork and having the change documented with them as well, so that her number stays consistent.
I won't dare to tell you if this is the right or wrong decision for you, but I agree that it's probably a good idea to have this discussion with your partner/husband/significant other before going further down this road. Names are tough...my husband and I found that we could only agree on one name, and that is the one our son wears today. It suits him fine, and that's fortunate, but I know of other situations where naming baby was more complicated. Good luck! (~~and as for worrying about too many other people's opinions...well, unless you are going way far out with the new name, they'll kvetch and get over it eventually...or not. If they decide to hang onto it, just let go...they'll be the only one holding on, right?)