You're not depressed, you're sad. It will pass with time, but you can't suppress it.
Dear Christeen, Oh, I feel for you. I know what it's like to lose a favorite pet. Nothing worse, really. About all I can suggest is asking your parents how come you cannot keep Joey? Tell them how you've been crying daily since he's been gone. Tell him how he sensed when you were sad and would comfort you. See what they say.
I CAN tell you this. One day you will be living on your own, you'll have a job to pay for a place, and then you can pick out a kitty that seems like a good choice, and you can take him home FOREVER. But for now, I would appeal to your parents about possibly reversing their decision for you emotional well-being. They likely will not change, but it won't hurt to ask... you just never know.
Fellow pet friend, Gail