I totally get that. I used to be the exact same way. I got rejected a lot by galleries/boutiques for years when I tried to sell my greeting cards to them, but one finally loved how quirky it was and took them in. I've been rejected by publishers as well for my comic and I got so fed up with it that I just did it independently for conventions. If it weren't for someone reaching out to the local comic book store to see if they had my series, I would have them in 0 stores right now.
Always feel not good enough. In the past few years, I learned that I'm far too harsh on myself.
When the time is right for you to take the plunge, just remember that rejection just means "you might not be a good fit there, but you can be a good fit somewhere else".