Mood swings hitting full force anyone?

I wasn't expecting this best friend to be there when I delivered since she's still in the "I'm still in college party girl" stage of reality tho she's out of college and hasn't been super supportive of my pregnancy. I've told her before that she doesn't have to come but she feels inclined to be there which is fine. However she responded to my possibility of my son coming late as "oh my boyfriend's birthday weekend is that weekend. I guess I can afford to take Friday evening off." This boyfriend hasn't been around longer than our friendship so her basically saying it will be a hassle for her makes me so peeved. I really shouldn't be this annoyed by it since I have no idea when my son will make his appearance but her just saying that feels really shitty even if I wasn't expecting her presence. I'm worthless than what I should feel and they can always rain check a birthday. I can't afford to rain check a labor especially at a moment where it would be more flexible to her. There won't be a second labor of my first son. It just doesn't work like that. I just feel like I'm over peeved for no reason. Anyone else getting annoyed over petty things?