Having problems with my best friends?

My best friends are called Abbey and Amber. Me and Amber were in France for a school trip for 4 days and Abbey's status was, "Woo my bff Amber's back from France tonight!" and she didn't even mention me. I feel like I'm always left out by them. They always go everywhere without me and it's hurting my feelings. I still want to be friends with them so what can I do?? HELP!!