Does my girlfriend want to break up with me?

Me and my girlfriend have been together for 4 months and whenever we are together everything seems great between us.

However it has been 2 weeks since we last saw eachother, which was at a carnival event the day BEFORE valentines day, She says she is busy and that she miss me, but I think she might be lying to me and perhaps even herself..

About a month ago, she told me that something "felt of" in our relationship and she was considering whether to break up with me or not (despite saying countless times how sweet I am and that she still loved me >.>), but we talked it through. I've asked her since then if she still felt that way, which she denied.

I am 20 years old and she is 15. I think she might just be confused (and young / busy with her friends).. but I am even more confused. I really love her, but her insecurity has made me constantly restless x.x

I miss her like crazy, but at least we have planned to be together on sunday - though I'm not sure if I'll be able to relax and just enjoy my time with her :(