Warning as I shotgun a bunch of data all at once, not trying to overwhelm you:
I'd go with Mirialan, male or female. Just for embracing the great span of the galaxy.
So Mirialan Matukai, love the allegorical. As Mirialan are a known jedi recruitable species, one question would be character age compared to order 66 and the second to why she wasn't a jedi conscript first.
It is already said they pick people the order would not have chosen, many children who fail the jedi padawan trials become members of agri-corps or medi-corps and explori-corps. One option is a failed jedi initiate who came upon the wookie with her time in the corps that brought them together when order 66 occurred and he kept her on the run with him since.
The other idea I had was that the wookiee knew one of her parents and he pledged a life debt to their child so he has always been the 'fuzzy uncle'.
Don't mind excess stuff thrown at me, I actually prefer it so don't worry about that. Just keep in mind my knowledge is that of the movies and a few of the older games, so the whole Agri-corps, Medi-coprs (Obviously something medical here?), and explori-corps are something I know nothing about. Also what would be some reasons for someone failing the trials, and also how long has it been since order 66 (Might've missed that part) and how old would she have had to have been to start and fail the trials?