over flooding her with gifts can really scare her or freak her out
she'll start wondering why you're giving her gifts all the time.
sometimes, there's stress after class not everyone would like to talk, perhaps maybe there might be family issues behind that as well.
i'm in highschool and these things can happen anywhere as well.
sometimes you can't be too clingy, you have to give her some room. this is called her comfort zone. giver her sometime to reflect on her day, instead of spending afterschool with her, try spending lunch with her. try meeting up in the morning to study for the class the both of you share.
* you will never know until you ask* honestly just tell her how you feel towards her and you'll know the result.
this of course is just MY opinion
hope this helps
-Jjdubbie:)