Bridesmaids' Mystery Dresses!

No, you're not. I would be 100% straightforward with them and let them know how you feel and that you would like to see the dresses. It doesn't matter if they don't like the color, they agreed to this and it's your wedding.

I don't think you are being unreasonable! this is something very common for brides and we see it on WW all the time. there's a certain level of anxiety we get when we hear that our bridesmaids haven't yet gotten their dresses and we worry if they'll be super last minute.

i literally had one of my bridesmaids get her dress THREE DAYS before my wedding -.- so i understand that type of anxiety. but as PP said i dont see anything wrong with you wanting to see the dress.

I did something similar to you in terms of letting my BMs pick their own dresses with certain criteria. I don't think you're being pushy or unreasonable. Maybe just reiterate how you need to see the dress they plan to wear before the wedding - and maybe say something like "since the month leading up to the wedding will be hectic with seating charts and vendor confirmations, I'd really love if you ladies could run your dresses by me before [some day in July]" or something like that. Good luck!!!

You are being so reasonable.

When the girls find a dress they like that matches your requirements they should send to you for a final thumbs up before purchasing. Often brides will give some basic criteria and miss something that turns out to be important to them. For example, I originally told my MOH floor length, dusty pink but then realized I had to specify no shiny fabrics when I realized satin and velvet were coming back in style and I wanted a more matte (chiffon, crepe) look. The bridesmaids showing you their dresses for final approval ensures that the overall look is cohesive and matches with the wedding aesthetic. If I had had more bridesmaids, I would have wanted to do mismatched dresses in either all shades of dusty pink or mismatched dusty shades (like sage green, dusty pink, slate blue, mauve, etc) and then it would have been important to see everyone's dresses to ensure that I didn't end up with three girls in shades of pink/purple and one in green, which would have stood out too much.

Reiterate your requirements to your girls, send some sample images (it could be actual product links to dresses that fit your criteria or just some inspo photos from an idea board on Pinterest) and then give them instructions. Ask them to send you photos of any dresses they are thinking of and not to actually purchase anything until you give the okay, and give them a deadline. Good luck!