I’m with you. I meditate and I have aphantasia. I focus on my breath mostly, but as someone with adhd, my brain goes everywhere. The key is to not scold your brain for losing focus, but instead once you realize, note that you lost focus, and then gently bring your attention back to the breath. Meditation doesn’t have to have an end goal or a focus point or imagery or anything, really. I just like to take note of how my body is feeling, what my mind is thinking, emotions that come up, etc.