Ruthie, I love your teal, ivory, purple theme. I'm not sure about adding navy to that, unless it is a color you think you will love. If it were me, I would use purple as the neutral and add teal as a splash of color. If the purple is dark, it will work as a neutral. Then it would be something like this:
purple jacket (I think you already have a teal jacket?)
teal/purple stripe blouse
purple tone on tone waistcoat or cardigan (okay, in my head this is a lovely floral print in shades of purple, lol)
Add more teal in accessories, like a scarf. Or add a teal top. If you keep the mostly purple theme, you can add so many lovely colored blouses (like orange, lime green, red/violet, all opposite to purple on the color wheel) at a later time.
Now feel free to disregard this post