Imposter syndrome
Growth begins at the edge of your comfort zone. That is when you get out of the things you are very used to and can handle yourself without any help. The fact that you are probably taking help or references from others to get your job done in a sense means that you are learning something new each time. So it makes sense that you feel like an imposter. But the more you do this the more comfortable your creative muscles will get over time in those areas.
Things that matter:
1. Are you able to ask the right questions?
2. Are you resourceful enough to figure out how to execute something new, by yourself?