My code

Ever since 1990 I think it was, when I was at school I made my own code. This is a code of english, with one character representing each english letter. I have written a few sentences here for you to look at. I can write this at reasonable speed. I use it sometimes in my diary or to write notes to myself. No one else knows the code, and no one has ever been able to crack it. But now on the internet for the first time, I guess that is another thing I risk.