Why don't you ask for an MRI? That will tell you if there is active inflammation. It's possible to have your CRP/ESR change. For example, I was diagnosed at 14 with juvenile spondyloarthritis (I'm on my mom's account!) and never had an elevated CRP or ESR. Around 18, my x-rays showed that I had progressed to AS.
At 22, my CRP suddenly started showing inflammation. It has now been elevated for two years roughly, but it goes up and down. So for me, 38 is really bad (range is 0-4 at this lab) but 7-8? Not so bad. It's all about what your normal is. We have never been able to get all my inflammation under control, so my CRP is always high. So we aim for the best control possible.
Before I had an elevated CRP I would have MRIs when I had a flare that lasted several months. Those generally showed either structural progression or inflammation. I went from Enbrel, to Humira, to Humira + MTX, to Remicade +MTX, to Simponi + Arava (at that point I developed inflammatory bowel disease) and then back to Humira because it was the one that worked best for me. I won't bore you with my long complex history, but because I ran out of options, I tried quite a few anti-TNFs twice. They did work the second time - in fact, some worked better the second time because I was given a higher dose (Remicade for example). They all worked for a while. Humira was like magic and lasted two years, but besides that, the others didn't work that well and didn't last that long and I was on steroids constantly.
Then I switched to Cosentyx (+ Imuran for the IBD) because it works differently - it's an IL-17 inhibitor, not an anti-TNF. It worked really well but I still struggle with pain, and need opioids to be able sit, stand, walk and sleep through the night. The pain is from damaged and fusing SI joints and damage in other joints. I'll be having a major surgery this year to attempt fix one of my peripheral joints. If that doesn't work, I will need a replacement.
But currently, the inflammation is mostly under control, which for me is fantastic!! My CRP has been sky high for two years, so this is good.
I guess all I'm trying to say is how you think about your situation matters. And that you shouldn't lose hope if your first biologic does not work or if the effects wear off. I am 24 now and can also get anxious, especially when I think of the future. But my dad has AS and has fused sacroiliac joints, some fusion in his neck and has had several hip replacements. He has significant fusion because of course biologics weren't available when he was diagnosed. He has still lived a good life and worked full time and still works full time. So I figure that it is possible. I do have a few joints that are damaged, but it's nothing like my dad's situation because we are lucky enough to live when biologics are the standard treatment for AS.
It is of course harder to think rationally when you are in pain. I would suggest seeing a psychologist. You have really change the way you think because not only can anxiety make pain worse, it can take over your life.