Each time you add a new aspect to your study and practice a little bit of doubt, anxiety or caution creeps in. Push through and it will eventually fade. Just like it did before. It's absolutely normal.

I think I understand where you're coming from. There are times where, whenever I'm actually working on something outside of warmup, I feel like everything I produce, even when it comes down to the smallest of steps, has to be good. This wastes so much time in my opinion because every drawing or sketch you produce is a step in the right direction no matter what. What I usually gotta do is take this into consideration and tell myself to keep at it, because eventually you'll gain the confidence you need to do a certain thing after enough practice and commitment. I've got a lot a lot to learn at this point but you have my vote of confidence that you'll get this down. Good luck!