As a study coach, I work with students everyday, all day.
One of the things I come across all the time is that students feel that they should 'learn' something instantly. They feel that if they've heard or read something, they should 'know' it straight away and be able to use and apply it. This is especially true for those of us who are perfectionists.
The truth is that learning is a journey. You go from knowing nothing, to 'discovery', to thinking about it, to knowing a little more, and struggling to apply it to different situations. Learning is not a 'switch' that's turned on as soon as you hear something. So I created a sticker for you, to remind yourself to have patience with your learning journey. (Find it here)
I also recorded a video for my students to discuss this a little:
If you're uncomfortable with your knowledge, then you're in the middle of your journey. Keep going!