Similar story here, from the POV of someone with moderate anxiety, and very mild depression (probably as a result of the anxiety). Medication made me feel less, which was preferable to anxiety, but CBT was a set of tools I've continued to use. I had so little insight into my own thought processes, and the ways in which I was unintentionally reinforcing my own anxieties. It's taken a lot of effort, over a lot of years, but with that basic set of tools I don't need medication and I don't have anxiety or panic attacks. Ever.

Still, if you did have that set of tools going in, but for whatever biological reason it didn't matter, then I would guess that CBT would be dust in the wind for you.