18m male is asking for how to deal with insecure thoughts about my 18f girlfriend

So essentially me and my girlfriend have been in a relationship for 9 months but I’ve gone on vacation to a foreign country. Recently she hasn’t been texting me as much and i don’t know much about what she’s been up to as she doesn’t really tell me anymore. This vacation will last 1 month and im struggling with insecure thoughts about her losing feelings about me, especially since she said before she broke up with her ex boyfriend she had stopped communicating with him as much on purpose. Im really worried right now because it seems as if she doesn’t really even feel like talking to me and I don’t really know what to do. I asked her before and she said she was just feeling “tired and sloppy” and “not in the mood to do anything” which includes calling, which I really want to since I miss her voice. What do u think is going on right now, and is my overthinking damaging the relationship in any way right now?