It will come @PatsyN, it will come. But only when you've grieved that person you've lost. For some of us this will be a brief time, for others it will be longer. I have walked nowhere near as close to the edge as you, but my internal world, my sense of self, has been completely upended and I feel like I'm sitting in ruins. I have not felt joyful finishing chemo. I type this to you with tears in my eyes. You have my empathy, my sympathy.
However having said all that, I am so delighted by your results! Rather than expecting joy, why don't you just sit with your new knowledge, along with the pain, acknowledge that it's there but place no expectations on yourself. Look up. You may be in the mud with dark clouds above, but those clouds are parting and you can see blue sky. It's there. One day there will be no clouds and you will be bathed in light. It's waiting for you and when you're ready, you'll be in the sunlight.
Hang tough through the next couple of weeks. You've been through so much, you've got this! You're a marvel and an inspiration. Big bear hug, Kate xox