well... imo... you can see her facial features are more older like I guess. However it makes sense to me why she didn’t grow, malnutrition can literally have permanent effects especially with height. So in terms of that it makes sense to me but yeah I agree at the same time.
SPOILER
Why does Leslie look exactly the same after the time skip. She doesn't look like she's 16. I wish they made her look a bit more mature I guess