Answere #3 (Patreon)

The mystery who is is solved. XD

She has the closest bonding with Sawati so she became a hunter. Beeing big means survival to her so she gaines as much weight as possible in the summer but since she have to be pretty active she can't reach a much bigger size than which is shown here. 

But if wanted I can draw a picture where she is bigger (a time where she doesn't have to be active or something for example).