My wife, Squeaky, rode my WR250F quite well on moderate trails in the Midwest. She is 5'5". Once she got on more advanced trails (rocks, roots, New England area) she had to step down to the TTR125LE.
Keep in mind, she did well when there were few and far between technical sections in the Midwest, but had trouble with balance/falling over in the tougher terrain out here.
We are now looking into a YZ80/YZ85 because she has advanced in her skills, but still needs to be lower to the ground for balance and control issues.
The 250F's are full size tall, I ride the WR250F and a YZ250, just touching the ground, and I stand at 6'-0". With you being 5'-6", you may want to consider that issue.
If you think, look at your parents and how tall they are, that you will sprout up a few more inches, perhaps the 250F can be grown into. At 13 years of age, you could very well grow a lot, and be able to manage a full size bike quite soon.
Good luck!