Design is not just what it looks and feels like. Design is how it works.
I once joined project that had been running for nearly 2 years. It had lovely, elegant screens, a fully responsive layout and a clean user journey. The only problem - it wasn’t the solution the project stakeholders wanted, they wanted a system to let their employees manage customer accounts, what has been built was a system for end users to manage their own accounts… Oops!
You don't want to build the wrong thing do you?
At this stage, don’t get hung up on what it looks like, focus on how it works. Then ratify your design with the stakeholders. Depending on your project and audience you could start with simple wireframes, before moving on to full-fledged prototypes
Don’t over complicate the sketches, is should be an outline representing the features and formats of the design not an illustration in fine detail. Don’t think about the aesthetics or colors at this stage, that can come once the design is ratified. A simple, uncluttered, wireframe encourages focus on the how of the system. Too much visual detail tends to drive the conversations toward the aesthetics.