As a fellow Disney Bride, who did indeed dream about her wedding since the age of five, I do understand your point of view about things "matching" perfectly. When you envision your bridesmaids, you want everyone to look uniform, you want the symmetry of the dresses and lineups to look "picture perfect" but as a person, you also need to understand that life (beautiful-always-not-so-perfect life) often does get in the way of what we envision, leaving us two choices. 1) you can either let the fact that your BM is pregnant take away from your wedding happiness

or 2) celebrate that while YOU are experiencing one of life's great miracles, so is your BM by having the wonderful oppurtunity to carry her first child.

The choice is yours, but I think there is only one logical option.
You need to set aside your views of "perfection" and realize that life has thrown your BM the miracle of a lifetime, just as
you have been given a miracle by finding the love of your life and having the chance to get married in Disney World.
My sister struggled with infertillity for over 2 years. My wedding took place right in the middle of her stuggles. She always was hopeful that one of those months, it would work. When we went dress shopping, we had to have a plan B if one of her invitro procedures actually worked. I would have been the happiest "auntie" if she had the oppurtunity to be pregnant at my wedding. But, it wasn not in the cards for her. She continued to struggle. Thankfully, 6 months after my wedding, she did get pregnant and I am now the auntie of 2 beautiful twins!
Life has a wonderful way of working itself out, but please rethink your feelings and realize that a wedding photo with a pregnant woman is beautiful, not an inconvience. You said yourself that you are not usually like this and would normally never be the kind of person to let this bother you, well, take your own advise and trust who you are as a person and work on focusing your energy on something positive, like how to help your BM during this special time (making sure she had a seat at the wedding, etc).
Things will work out, but you need to focus your time on constructive things and enjoy your wedding planning. This time will go by very fast. Don't waste it on silly things that could only potentially hurt someone you love very much.
No flames intended for you, just wanted to offer some advise

Best wishes for a beautiful wedding
