Problems

Okay so I have this friend and we've known each other for a while so I guess you could say we're close. The problem is she is really aggravating and annyoing and always gets me mad. She makes problems out of every small thing. I was suppoed to be joining dance with her. She already joined and I was going to join this week. But my period is coming and I don't want to be at my first day of dance and have my period. So I was going to reschedule and go the week after. I told her and she got annyong and was like "don't come. I'm going with someone else" and stuff like that. It's just been really getting annyong. I didn't know who to talk to so I decided to come on here. I really don't know what to do anymore.