I'd suggest reading some of the posts in this forum, that date back over the last several months or years. There are many beautiful posts and many people who have been exactly in the same place you are now. You are not alone. This doubting is very common and everyone has some of it.
Recognize that the doubting is part of the your brain trying to scare you. You can look at these thoughts (the doubting thoughts) as just thoughts; nothing more.
You'll see when you read the posts that others have gotten through this period; and you will too!