I am MOB. I have found an ivory gown that is beautiful. It comes with a white lace and beading that makes the dress. My daughter's dress is lighter and whiterand a different style. Is it approprate for me to wear a dress that is such a light color and is almost white appearing because of the lace. The wedding party are wearing pastel colors as this is a spring wedding in Florida.
It is becoming more and more acceptable to wear a range of whites at weddings these days (typically for guests). However, in my opinion your dress sounds a bit to close to the bride's dress. One of the major concerns for any of those close to the bride, is not to take eyes away from her. The guest could think that you are the bride.
It would be best if you chose a color that compliments the bridal party's dresses.
I realize how disappointing it is when you have found that perfect dress, but cannot wear it. Perhaps you will find another reason down the road.