What you said in your first post regarding end of treatment is extremely, extremely common. I think in my first year after treatment, I had 2 MRIs! One for shoulder pain and one for hip pain. Of course, it was nothing. Just about all of us keep a recurrence in the back of our minds, simply because we know it is possible. Anyone who says it isn't, is in denial. Having said that, it just took me some time to adjust to that. Like Alvita said, you will be very closely monitored. I pray for the day that a simple blood test could detect cancer. After a couple of years, I didn't even get bloodwork, since there isn't anything that would indicate the cancer has returned. One of the most difficult things I heard after my diagnosis was learning that there was no testing to be done after treatment unless I had symptoms. MRIs, PETs, etc. are extremely expensive, and insurance companies just can't pay for the zillions of them that we would want.
I know you will get to the point where you won't think about this as much.
Hang in there. Very happy you have finished with treatments and can adapt to your new "normal" like many of us.