The Dane is halfway through a two-year loan with Borussia Monchengladbach, where he is wanted permanently.
However, Chelsea rejected a €20 million offer from Gladbach over the summer for the youngster.
Asked about the situation, Christensen concedes everything is up in the air.
"I have not spoken with Chelsea about my situation. It is a difficult decision, which I have not had the time to think about," he stated.