Interesting subject and sounds like you are in a place that many of us have been in. A dark place, where all hope seems gone, and nobody, apart perhaps from the people on this forum can understand you.
When I was diagnosed I went from "you have cancer", to "you have stage IV cancer" overnight so I was very certain that I had no hope and when I was first on this board I was superscared as I knew that I had very little chance of surviving for any length of time, let alone becoming and staying cancer free.
I came across a fell by the name of Eric, that we all knew as "Brown Bagger" and I talked to him a lot, a little on this board, and a lot more via messaging. The one thing he taught me was that my focus was all wrong in that I was focusing on the negative, that I could not control, and that was determining my view on life, or what possibly remained of it. He had a motto, which was Motto: Live your life like it's going to be a long one, because it just might, and then you'll be glad you did.
It really changed things for me. I am not going to say that the worry and fear went away, but I tried to focus on enjoying life and pushing the fear to one side. I wasn't going to let cancer decide how to live my life and I would try to enjoy it.
As for calling myself a cancer survivor, I am not too much into that. I have had cancer, that has changed me as a person in many ways, and I try to take the positives from it. I can say I felt less worried about cancer at about the 3 year mark but for me, and most likely you, that was a lot of scans, a lot of worry and even now I don't call myself a cancer survivor.
I see my oncologist in about 1 month which will be my five year mark, and if he calls me a cancer survivor I will feel a lot better as he is super conservative. Otherwise, I keep plodding along doing what I do.
P.S. Did you get your PET Scan results and if so what did they say?
Stage IV Rectal Cancer (39 Year old male at dx)
pT3N0M1 (wish that was M0)
Diagnosed 05 Dec 2012
LAR 05 Jan 2013
VATS 27 Feb 2013
FOLOFX April 2013 - Sep 2013
Clear Scan 03 Dec 2013 - 27 Feb 2018
Port Out 26 March 2015