Mother of bride not attending dress shopping

I had told my wedding party the date and time of my appointment about 3 months ago. When I went to confirm it with everyone my mom said that she's going out of town this weekend. She planned a trip over my appointment even though she knew and confirmed that date would work for her. I'm actually really hurt. My dress shopping apointment is Saturday. Even though I have a huge support system coming it's still really hard to know my mom's not gonna be there. I never once would have imagined her not being a part of this. I asked her if she could reschedule her trip when I found out about it. She told me she couldn't because she already put money down. I just want my mom to be there. I guess that's what happens when your the youngest. I feel totally unimportant to here.
Also I need dress type suggestions for a short curvy girl.