This is a good question which I think haunts many, irrespective of whether it’s about making a zine or creating another equally challenging piece of art, visual, textual or tactile! I don’t think you need to get hung up on what the zine is going to be about, or its theme right from the word go. Be playful and think about it in terms of process. You compare yourself to that of a chaotic mess, so maybe you could explore that further by kicking off using a collage based approach to your zine. You mention you have more artwork than text, so this does suggest a possible collage route. It’s often suprising what king of message/narrative comes out of trying this approach.
I’ve recently used collage, which I’ve always loved, to build up a 24pp A5 zine, building up the collage from a selection of collected images and then overlaying that with cut-ups of a short story I wrote. Strangely, and almost subconsciously, a theme began to grow within the zine which I wasn’t aware of at the start. I will post up an image of it when I finish printing and binding it. Give it a go! Julius