You're far from too big for her, especially for an Arab. They're some sturdy little beasts. I wouldn't worry about her winter coat too much, nothing a curry and some elbow grease won't fix. I would check her for a fecal egg count (worms), and I'd be more concerned with her wry tail, if she consistently carries it to the right like that. I'd also be looking at her left hip area, I also see she's standing without weight on that left hind. So, PPE for sure. She's a cutie.