What if the last treatment isn't the last treatment?

Background: Diagnosed with ovarian cancer in September for the first time. Powered through surgery and initial treatments, ready to take on whatever the doctors threw my way. Now, I'm finding it hard to get back there. I'm supposed to have my 6th and final treatment on Monday. I am fully aware that to many I probably sound very whiney here, because so many people have it so much worse. My CA 125 has continued to fall and the doctors were hopeful, until this last treatment showed that it still wasn't as low as they were hoping. I have one oncologist telling me to expect 2-3 more treatments and I've lost a bit of my courage. I'm tired. I'm weaker than I was and I want to keep working and living a normal life. I know there's no trick to knowing what it'll take to be done with treatments, but it's hard no longer having a countdown or the hope that they're wrong.