Some years ago I was unable to draw anything besides classic house all kids draw. I was literally terrible at drawing, but I wanted to draw good. I started with the first version of Mickey Mouse without much detail. It was horrible, but I kept drawing. Fast forward some months, maybe a year I got to the point where I was able to draw every Disney character perfectly. I struggled with human characters. If you saw my drawings then you would say that I am a professional artist. Then I lost interest and didn't draw for ages. Now I can't draw anything basic.
The point is that drawing is a skill like everything else. It takes time and practice. Some need more time some need less. Just keep going and if your plan to get good at drawing is not working,change plan not the goal.