Be gentle with yourself- take the weight off first-- the weight you carry to say it "right" -- or exactly "perfect" their is no perfect way to describe yourself. Do you have someone you know personally who could help you write it? You don't have to tell them the specific issues you're having... but sometimes other people can find the good in us more than we can find in ourselves. we can be our own worst enemies. However, I am a writer and people ask me for help with different things (similar to what you're describing all the time) Find someone you know who is good with words... who says you have to be the one to write it? It's not like a term paper or major project for the job is it? Just a description. Go get some help with it if you can! It's so normal to try to get some tips.. just like people get tips for resume writing!