How do I design a circuit instead of just reading schematics?

You can read a schematic and understand what someone else built. Creating one from a blank page is a different act, and the openness of it can overwhelm you. Where do you even start? That feeling is normal. Reading and writing are different skills in any language, and circuits are a language. Design gets less overwhelming when you stop trying to see the whole thing at once and start from what the circuit must do. What goes in, what should come out? From there you work in known blocks, a power section, a signal section, pieces you already recognize from all those schematics you have read. You are assembling from parts, not inventing from nothing. Start with a simple, well-defined goal and design just that, one small circuit that does one thing. Use the building blocks you already know. Get it working, then try a harder one. Design is a muscle built through small finished projects, not a gift you either have or lack. You already know the vocabulary. Now start writing your own sentences.