How do you make her appreciate you more?

[Sci-Man]

First of all, thank you for reading this, it is much appreciated:

On a summer holiday, I came across a girl from the hotel who found me on a social media site, despite not talking to each other (she came on holiday not long before I left). We are both college students (I'm a year older). We have spoken to each other almost every day for 5 months via text message & occassionally skype. She's smart, nice, cute, and she feels special to me (unlike most girls that I have known). She smiles when I speak to her & seems happy.

We've been very close for those 5 months, and I really don't want this to end. Recently I asked when would you like to meet up and she said in the summer, which I agreed to as we have exams before-hand. I said it would take time & I want to take it slow as it's difficult, but we can do it, and I might be moving not far from her to a University in September (possibly). She seemed shy about it & barely made eye contact. We used to talk a lot, laugh a lot and smile a lot.

She said I felt special to her & always make her smile a few weeks ago, because she was really down about her education. Then, I made the effort to speak to her when I was on holiday so she wouldn't miss me. We've talked for ages & I've been nice to her, when she was down. However..

I was talking to her on Skype whilst she was messaging someone, which I found rude, & I have a feeling it's someone she likes, and she has been recently distant with me (stopped making conversation). She has said I trust her & she trusts me & I would wait for her, I've asked to call her, she said she is busy, and says it more commonly, so now I'm giving her space until it's too long to wait.

So I'm thinking of calling her very soon in a normal conversation, and then explain this. What should I say & do? Should I wait? I've put so much effort into this, been nice, and it seems like she just wants attention, I don't want to give up. She does seem a little immature & I don't want to be hurt in the summer, even though we have agreed to do it.
Only I have been making the effort recently, she always seems busy, and I don't want to nag her.