If your fabrics in your flowers have bright white in them, like the pink & white check...they are most likely fighting the gray you chose for your background. Your flowers are bright pure tones of color, the background color is more muted (greyed). a solid pastel color for your background might make you like it better. If you like the gray best, remember that the quilting thread will be another opportunity to get the top to be cohesive. A varigated quilting thread color can liven up the gray and still relate back to the flower colors. Love your flower color choices.
Tammy