Impersonating the Bloody Baron
I think that making use of the Veela ancestry is a good idea, although the 1/8 is a slight setback.
I'm not sure how you would work out the amplifying, but I wonder if it would be realistic. Would she use a spell or take a potion, or is it an innate skill like Metamophmagi are born with?
The pride I completely get. Look at her parents: Fleur, former TriWizard BeauxBatons Champion. Weasley, Bill. You don't get more stubborn and proud than a Weasley, and add Fleur, well, need I say more? (actually I probably do, but I can't think of the right words right now).
Her looks seem fine, except maybe the chubby from spoiling. Curvy, ok, she's part Veela, but she has 2 siblings, which usually means less spoiling. She also seems a tiny bit too nice, but if you introduce and play around with some flaws she will become less Mary-Sue (from what I think you mean anyway)
Gryffindor and a little bit lazy also seems reasonably in character (if I can call it that), as she can always charm some of the male professors at least into giving her decent marks...not something I'm suggesting she does (pride and all) but if she really needed to, I'm sure she would.
So I think that everything here seems fine except the control of this amazing Veela enhancing ability and the possibility of turning a canon character into a Mary-Sue. Good luck with controlling the bunny!