These are just some points I think might help, good luck!
1. Have confidence in your own work. You think that successful authors didn’t doubt themselves at some point? They just kept striving to succeed!
2. Take those authors you keep comparing yourself to and use them as inspiration for your future writing career. Fear is such a negative emotion that it will only set you back, overcome it and change it into motivation!
3. Write. Always. How can you work on improving your craft if you aren’t practicing it daily?
4. Always have something on you to write. You say that you don’t have any room for a notebook or some paper and a pen? Easy. Use the Notepad feature on your phone or iPod.
5. When you start a story you like, finish it. Work at it like there’s no tomorrow and instead of following the urge to start another story, simply write the ideas somewhere else for later use.
6. Remember that one day your writing will affect a future writer just like successful authors intimidate you, so what you’re feeling isn’t an exclusive and rare case.
7. Everyone has a different style. Just remember that YOU HAVE SOMETHING OF YOUR OWN TO OFFER THE WORLD just like your favourite authors did/do.
8. If you keep looking at your work and sighing in disdain, don’t just give up. How can you improve it?
9. Why do you write? Think about it. Is it worth giving up your dream because of the fear that you have of other authors?
10. Not all great books are/were written in months. Many are written in years. John Green has admitted that The Fault in Our Stars had been with him for years before he finally wrote the story. I know successful writers make it look easy with their fluent diction and poetic prose, but do you honestly think that they didn’t lose sleep over their manuscripts like you do? They’re human too. They got to where they are by working hard and believing in their work, so don’t give up. Never give up.