Obviously, enough that she can plausibly take on the monster at the end! NOT an enormous ancient red dragon -- but deliberately intended to be as powerful and dangerous. With lair effects and all that.
She's sixteen when it starts and twenty-five when it ends. The progress is not even -- having three pregnancies and four children WILL slow you down -- but even when at home with the children, she's still fighting sometimes, when the monsters go for the stronghold.
Pondering, pondering. . . .
More big, dangerous,dramatic ones than little ones, though those are a background pest.