There are a couple of things that you might want to consider right now. First of all, anxiety can and will evolve. Just because you didn't experience low mood before, doesn't mean that experiencing it now is meaningful or significant. It's very common for low mood/depression to co-exist alongside anxiety. I have a suspicion that the therapy you are getting is causing you to over analyse the anxiety and mood you're experiencing, and I'm not sure that has any value. Analysis is the antithesis of mindfulness and acceptance. I don't see how you can successfully do both at the same time.
At the start of my journey with anxiety I received a course of CBT (10 sessions) which I found incredibly useful. In some respects CBT is 'ignore it and it'll go away'. But it is also one of the most successful methods of treating anxiety. Perhaps you should look into CBT sessions instead of (what sounds like) analytical therapy? If your therapist is supposed to be doing CBT with you, I suspect she's not the right therapist for you, in my humble opinion. In my experience of CBT, there was very little in the way of 'why'. It's ok to question a reaction, but going too deep can only ever result in confusion I think.
The current global situation is very oppressive, even if you are ok financially. Sitting indoors all day is not how we are designed to live, and in some respects that alone could be a major contributing factor in the way you are feeling. Not getting enough vitamin D (for example) can be more than enough to cause severe mood changes. Anxiety isn't just stimulus/response. It's bigger picture than that. Your experiences over the last 10-15 years are what got you to this place, not the last few hours.
I'm also against medication as a personal choice. I accept that some people benefit greatly from them, it's just not for me. Knowing that you can recover without may give you some light at the end of the tunnel in the short term.
I think the first thing to do is take a view on your therapy, and whether you can make some adjustments for the better. Is she right for you? Would you benefit more from a different kind of therapy? Do you need a short break from therapy? Are you able to commit time and mental energy into learning about mindfulness and meditation?