Looks fine to me also CM. I'd keep on keeping on with what she's on.
Some dogs are just lean, raw boned types, got one here the same, though mine eats like a horse and leaves his bowl spinning!
So many variables that can have him going from a show stopper to a rescue case, harder graft, not enough graft, longer runs, colder weather (when out), knocks and cuts, diet changes, wormers and medicin etc etc... And over the years i've tried to combat his weight/condition through diet alone but come to realise all those different things are just the norm and these days i keep to a good diet