Confidence comes from experience rather than skill. There’s no easy way to gain it, it’s something that happens over time the more you practice and the more you experience it.
As designers, we’re always learning and doing new things, and that means we’ll always be feeling self doubt about something new we’re trying. Instead of letting the self-doubt debilitate you, realise it’s simply a part of the learning process.
If you think you can’t, you can’t. If you think you can, there’s a chance you’ll make it. Sometimes a mindset shift is needed to start gaining confidence. Have some faith in yourself but set your expectations. Confidence takes time, you won’t become super confident overnight. But know that you can get there eventually.