Easiest one I can think of would be "Vows". Or you could change it to "Vowels" so that the pronunciation is clear, but that would look a bit silly ("... and her boyfriend Jack Consonant..." ;-)

Or you could just accept that people will mispronounce it, and think of your name pronounced as "Vohls" instead of "Vowels". "Coh-lin" Powell is an obvious example of that, since his name was pronounced with a short "o" until his family moved to the US and found that Americans say the name "Colin" differently.

Graham.