OP, I'm sorry you're having such a rough time on here. I guess the verdict is that the majority of people (on mumsnet at least) think a bridesmaid should wear whatever you've agreed and smile nicely in the photos. I happen to disagree:
- You may as well just have a dress code for all guests so you can get everyone to wear something appropriate and then tell them to smile.
- If that's all you want from them, you should pick the most photogenic of your guests to take centre stage in the photos to be bridesmaids, rather than your closest girls/women.
I had one bridesmaid who was my (very photogenic) sister. She read and sent emails about wedding stuff in the year before, nothing substantial, more like links with "pretty!", as did my mum. She came with me dress shopping and to my final fitting. She organised my hen do and did a DIY crafty job. I also had other friends/family doing stuff on/before the day to help out. They had all shown an interest and had offered help.
I was definitely not a bridezilla, but needed some help to plan a fun party, and more help to make it happen. I didn't really have a colour scheme, flowers, chair covers, favours so didn't spend time talking about them. I didn't bring up my wedding in conversation but did answer questions if asked - mostly "everything ok?" "yeah, fine thanks".
When close friends of mine have married, I have shown an interest and offered help, regardless of whether I was a bridesmaid.
I have interpreted your posts on this thread as disappointment that one of your closest friends doesn't appear to care about you. I think a good friend should show an interest in your wedding, just like they should about your new baby/job/house/hobby. That doesn't mean you have to burden them with a mind numbing level of detail. I think a bridesmaid should offer help which is practicable for them to give. A bride should be considerate to her bridesmaids and continue to be interested in them. The wedding day is all about the bride and groom but the preceding year is not.
YANBU to be disappointed but there's obviously a massive divide in expectations. I don't think you can do anything really, just wait and see how she is on the day and after.
Have a lovely wedding!