Hello,
Wow, only 14 years old. Good for you for being so passionate about something. Don't lose that. I am a new writer and about to start up a publishing company for youth and my advice to you is not to give up. Whenever you have a good idea, write it down. Dedicate a notebook or two to your ideas and keep writing them down. Even if it's just a sentence or two, you'll never know when you might come back to it. About your fear of rejection, I haven't come across anyone who isn't scared of that. I have been rejected many times (19 times on one manu_script_) and you learn quickly to accept the rejections as learning tools. I have developed the sort of attitude that whenever my work is rejected, it just isn't the right timing for it yet or the publisher has just passed up the best book ever. I love the work I produce and when I sit down to write, I pour my heart and soul into it. That is what matters. You have to believe in yourself 100%, don't falter even a little bit because when you believe in yourself and your work then others will too. Get some attitude. Your work is great and if you don't get it out there then no one will see the greatness either. Good Luck!