Very good likeness there!
But I do see a few small differences. There are some very small things that could be explained away given the passage of a few years after that school photo.
The fold of her upper eyelid can be seen all the way across her eyes in the Alcala pictures. Can't see that same detail in the school picture.
The spaces between the bridge of her nose and the inner eye, isn't nearly as full as it is in her school picture.
Her lower eye fold or puffiness under eyes are also much fuller in the School pictures.
The inner edge of her eyebrows have more hair extending towards the middle of her face in the School pictures, but I can see in the Clitheroe picture with her glasses, that area has been plucked. The area looks like it has been plucked recently (in the last week or so) in the Alcala pictures, meaning no regrowth that I can see. So if she was a runaway living on the streets, she had to have some access to tweezers and grooming. I wonder if Alcala provided this for her and his other victims. High unlikely, just a thought.
I think she also has plucked her eyebrows going toward the side of her face, making them look thinner and not as down curved as they are in her school photo.
In the school picture her chin is also a bit pointier than the Alcala picture. It could be just the frozen tense smile we all had for school photos that make it look different, though.
Just by the loss of fullness of her eye areas, while her face doesn't look "thinner" I think those pictures were probably taken a year or two after she disappeared. We tend to lose some of that youthful fullness (especially around the eye areas) in our later teens. I'm sure being a runaway in stressful conditions could speed up that process, though.
The rest of her facial dimensions seem to match, in my inexperienced opinion!