Of course, design is "function" and very tied to user experience. But design is also art.
And art takes its roots from creativity, new ideas. Of course discipline, technique and lived experiences also play a role in that. But let's focus on the pure creative process, figuring out stuff along the way and trusting the process.
Sometimes, things are blurry in our heads. Multiple ideas fight, and it can be hard to make things work right away. The solution is simple: just let everything sit for a while. Time is one of the most important things that can truly help shape things up. And I'm not talking about a night or two. It could take days or even weeks.
This portfolio took months of design, inspiration gathering and idea collection.
Letting ideas sit is a great start, but revisiting curated inspiration, and thinking about exactly what you're designing and why once in a while is really helpful. It helps you better remember the goals, the main path you want to follow for a project, and not let your brain overthink it too much by going everywhere at once. Of course, experimenting, feedback, collaboration and constraints make the process more active and thus better in general.
Design begins with a large spectrum of choices, but has to end with a pretty narrow way of seeing things.
And this whole thing can be generalized. For example, when learning a new concept in science, something hard to understand at first can seem simple a few months later. It just takes time (and practice along the way, similar to the "reviewing ideas" step for design).