The thing is, Luna and Neville were never together. They're only friends. The only reason people think they should be together is the movies. Anyway, J.K.Rowling herself said the Neville ended up with Hannah Abbot, a Hufflepuff student that was mentioned in the books a few times.
again, its lovely ginnys a bit off... her eyes are brown, not blue, and i always imagined her hair as being a lighter, more gingery red, to differentiate her from lily. and lunas back leg looks a bit funny. but i LOVE your romione, and your nuna even if nevilles hair is a bit dark.