Purpose in life is a tough one. I struggle with it myself. Every day once felt like drifting from day to day. The only changes I made was a found myself a supportive boyfriend, and a good job to keep me going.
My T always talked about goal setting. I never really thought that would work cause I thought it was all psycho babble bull crap. I was a cynic and didnt really believe in the mental health system and despised the groups I used to go to because I thought they couldnt help.
But the goal setting did. I set three small goals that I knew if I accomplished I would be happy. And I have two out of the three accomplished and I feel closer to my understanding of my purpose.
I dont know if it will help, but try setting a small goal and see if you can achieve it. It may help you find a purpose.
Hope that helps you