There is an issue that arises with many academics, especially young ones starting out. It is called Authenticity Bias and is the feeling that I'm not really smart enough to be part of this community. Everyone else is smarter than me and I can't believe that they are really accepting me here.
You are exhibiting some of the symptoms of that now. I've done everything I can, but how can it possibly be enough? Know that this is pretty common. I don't know that there is a simple way to overcome it other than perseverance. As you gain more experience, you find that you are, indeed, just as fit as other people to practice your art.
The other issue here is that this is an early experience in a complex undertaking. Mistakes can be made. Experts make mistakes and are sometimes misled by a variety of factors. Mistakes aren't normally career ending unless they are serious moral errors.
Another thing you will learn is that as you do more work in your field and write more papers, etc. your older work will look a bit naive. But that is just a result of learning and growth. If in ten years you are a lot better than you are now and your ten year old papers don't seem up to your then current standard... well consider the alternative. If they do all still seem great you haven't learned much.
I suspect that, as you have taken proper care, your current work is fine and that others will also find it fine, even if they recognize that you still have more to learn. And just as authors can, and do, make errors, so can reviewers. Evaluate everything you hear from peer review, accept what is valid and question what seems invalid. In the normal course of things you get a chance to revise a work before it goes for publication. Every academic experiences this.
Even poets often revise their work with the help of peer review. Some of the best, in fact, have published final works that seem to bear little resemblance to the original poem. Feedback helps.