So upset need advice

My sister just got engaged Christmas 2014. She asked me to be one of her bridesmaids even though I live about 8 hours away from her, I told her that I would drive out there when she wanted to look at dresses or needed help with the planning no matter what.  She hasn't kept me updated on anything about her wedding and I usually find out stuff from my other sister or family members. But today I got so emotional because one of her other bridesmaids texted me saying that they were dress shopping right now and that she would send me pictures. My sister hadn't even tried to contact me to see if I wanted to come and be with her even though all her other bridesmaids are there with her now. She doesn't have a date picked out yet so I didn't even realize that they were looking at dresses so soon... I feel a little left out and wanted to share that special moment with her, but right now I feel like she doesn't even want me in her wedding now. I just really need advice... Should I ask her if she even wants me to be in the wedding still? I just feel so heartbroken, I know it's her special day but I don't know why she would have asked me to be her bridesmaid if she doesn't want me to help/participate in anything