First you can only guess the age of your snake by size and weight, but then its not going to be acurate. Just a guess for sure. As for the feeding, if its eating Pinkies, Im assumeing its a young snake, offer it a meal every 5-7 days. If it eats great, if not, dont worry just try again the next feeding day. Balls do stop feeding for many reasons. How are your temps and set-up for it? Pictures will also help. We can give you guesses on age.