I used to be you when I was in 19-20. Grow up.
You'll find out she couldn't talk to you because it was some silly shit such as her phone battery died. You will still lash out your insecurities at her in the form of anger. Soon enough she will get fed up with you because this is not the first time you've done this. She will break up with you in less than six months, and it will be a very valuable lesson if you decide to learn from it.
I really needed to hear that even though it was directed at the OP. I'm not as bad as him where I need her contact that often, but I need to watch my insecurities.
Thanks.