so annoyed

Is it really a big deal to miss one appointment? I have my 32 week checkup today and I can't make it. They were pissy with me because I couldn't come and the only day they have is Friday but I have to work. And I can't really take it off because I've been working this job for less than two months and I just asked for this past Saturday off because of my baby shower. I'm sure they wouldn't mind but I'd hate to ask again especially on such short notice. So they called me back to reschedule. She had to have a reason why I couldn't make it(which I understand in a way but if I can't make it I can't make it I shouldn't need to give you a reason) so I told her I have a scheduled 4D ultrasound tomorrow(at their office) and she said it either has to be Thursday or Friday. But I told her I have to work. She said I needed to be compliant with the doctor. And it has to be Thursday at 8, 11 or Friday at 11:30. Which I work at 11 both days. So I just said I'd do Thursday at 8. But it's just annoying they're forcing me to come when it's just a 5 minute check. So now I have to get up at 6-6:30(which I know people do everyday it's just annoying when it could be unnecessary to me) to get ready because the doctors office is 30 minutes away and my work is in the next town over from the doctors so I can't turn around and go home because I'd have to come right back for work so I need to find something to kill time. My other doctor was okay with me missing one of my short checkups and just said they'd see me the next one. Maybe it is a big deal at this point in pregnancy, idk. I'm just annoyed because they were so rude about it which shouldn't be surprising because I've always had problems with them being externally rude and just a nasty attitude.  Ugh okay rant over.