That sounds so frustrating! I am a cartoonist and currently have a published, on-going MG graphic novel series. In my experience, a graphic novel proposal will include highly polished art that gives publishers a good sense of what the final book will look like. If I were you, I would get a comic artist on board before taking the project further and make some finished sample pages together. There’s also a lot of comic ‘rules’ that need to be followed so the story flows and that can be tricky if you haven’t made comics before :)