The writing system is called 21E™.
21E ™ is a phonetic code for writing secret messages in English devised by Kali Woodward who initially invented it to help his son learn to read. It uses 19 letters from the Latin alphabet plus 27 special symbols for vowels and some consonants. There are three styles of 21E™: print, script and condensed, in which vowels are written above the other symbols/consonants and can be stacked when they occur together.
The condensed script is what I use daily to keep track of important things at work but no one else can understand it. I really like this script because everything is written out phonetically and is easy to write in. It is the first script I have actually been able to use on a regular basis.
This is short and sweet but I hope you enjoy it and maybe you can learn it and write things down, like a journal or diary, and keep it secret!