The 20-year-old has scored seven goals in the Premier League for the Toffees so far this season.
"It was not the fact that I was not wanted, I was wanted but I had to make a decision for myself," he told BBC Sport.
"I had to analyse what the best was for me. Imagine if I was playing Chelsea now, I would play maybe five games maybe score one or two goals.
"Look now I'm playing for Everton, I've played eight games and scored seven goals. Everybody in England is talking about me about my performances and as a player I'm improving, I'm having that certain consistency in my game."
Everton are currently seventh in the league table, while Chelsea are third.