"You always get better as you get older and more mature," said the 23-year-old. "This is the first time I have been playing very regularly, except for when I first joined Chelsea, which is a long time ago now.
"Now I just want to play as much as I can. I have always had confidence in my own ability but Harry is now playing me every week which I am thriving on at the moment."
Johnson is determined to put his spell at Chelsea behind him.
"It was the right decision at the time but as it worked out, I lost two years of football," he added. "Every player needs games, it doesn't matter how good you are."