3 month check-in

Yesterday I had my 3 month visit with my Oncologist to do bloodwork & feel for any new abnormalities. The CBC bloodwork came back "perfect" according to the Dr. but I find out the results of the rest of the tests (tumor markers being the most important) on Friday.
This is routine for me at this point so although it brings some anxiety with waiting, it's just regular I guess.
The reason I'm telling you this is really just to vent, but it's what's swimming around in my head right now.
After she checked me out we were talking about any current issues I'm experiencing & I asked what my original tumor marker was when I first came to her (with the tumor still in my breast & cancer in my lymph nodes). She tells me it was 19.6 & I asked what was normal range. She says "Anything under 38". SO...my tumor markers were normal then, but that's the only test you're doing now to determine if I have cancer again? Let me say that the 2 friends I have that are survivors also say their doctor does the same thing for them & they've always had normal tumor markers as well. I asked her what they're looking for in addition to that to see if I've had a recurrence. She says that they check my body for any signs of tumors and look at my bloodwork. Other than that, I just need to be diligent in letting her know if I'm having issues like headaches or bone pain. Well, seems to me that if either one of those things happen and it's due to cancer I either have a brain tumor or it's in my bones...doesn't sound promising!
She said she would order a PET Scan if anything came up, but they don't like to do that too often unless it's warranted because of the level of radiation. In the same breath she says "We still have to be very vigilant in watching you because the cells were grade 3, spreading quickly & your age also made it more agressive". Awesome. I just hate hearing that word "agressive", it's pretty ugly, ya know!
Don't get me wrong, I'm not upset with her & I know she's doing what is "standard procedure" but how scary is that? I feel like there's a chance that it could come back & be a lot worse than before without anyone knowing until it's really metastasised to an area where it's harder to find and therefore treat.
Another scary thing to me is that I pointed out to her that I never had a PET scan to begin with. I had an MRI & a CT scan which are considered acceptable in finding cancer, however, neither one picked up on the 3 lymph nodes that had cancerous cells in them. Again, scary!
I know I could (and do sometimes) work myself into a tizzy every single day worrying about it coming back & how I would know, etc. but I need to just give it to God...again! I do realize that He healed me once & I have full faith that it could happen again, I just struggle with fear and worry and I soooo hate that about myself! All I can do is pray though & trust that between myself & the 2 doctors I have frequent check-ins with, we'll know if there's a problem & be able to address it.