I still think your fabric selection is okay, but if you add some white and some really dark, navy blue....that might also help you... When I said you had two colors, I was counting the two shades of blue....dark blue and light blue.
Thanks for admiring my two Surf Songs.
Since you have mentioned purple....I have to share my purple Bargello. It is just purple and white. Pretend it is what you are playing with in blue. Might help. The one fabric that has purple and white in it added a bit of surprise, I thought. Everyone told me not to use it....but I like it. Visualize blue where the purple is, and I think you can see that it might be a good look. Your blues are not as dull as you are thinking.
Dina