Simply knowing something, does not make you a master of the topic. For example, I can saw, sand, fasten, and paint, but that does not make me a master craftsman or carpenter. I have many examples of projects to back up that claim. In order to reach mastery, there is a need to engage in the arena of understanding and frequently battle (and defeat) the master's archenemies - procrastination and apathy.
However, frequency is tough. Especially in the early stages.
That is why getting started properly is important. New challenges need to be broken down into manageable parts. Take it slow. As you improve, your speed will increase - a sign of progress.