Happy birthday! What a birthday gift you have given to yourself! Awesome!
Yes, green apples are great, mixing with Celery is also great. First I would dilute the juices with water and then go with juices. It is important to chew your juices to activate your stomach juices and mixing of saliva.
Pink tongue is a good sign of clean body. Although Dr. Shelton says in his book that one should not stop the fast if the tongue turns pink but the true hunger has not returned. And if the true hunger returns but the tongue is white by all means brake the fast.
Congratulations! You are an inspiration to all of us.