AITAH? My siser (25) booked her wedding dress fitting the day before my birthday. I planned on having my party and a sleepover with some friends on the day before, but now my mom will be too busy to care. She claimed that it was the "only available date" but my mom admitted that they were open the next weekend, which was the day before easter. She claimed the booking was made sooner because her wedding is in September, and it's currently April. I personally disagree, as she hasn't even sent invites out yet. I told my sister i think she should do it the next weekend, but she said I was making a big deal and that it was "her big day" and "very soon". Keep in mind, last year my mom wasn't there for my birthday because she had, an auction event, which hurt me badly as it was my golden birthday and both me and my moms lucky day.