Lithium is what I take at the moment and works well for me (as a bonus — I take it mainly for bipolar disorder) with few side effects, but you don't seem to have been so lucky. I also sometimes take benzos for the very occasional state of arousal (I don't stop to wonder any more whether it's anxiety or agitation).
SSRIs and SNRIs are useless for me, too.
I didn't get much out of beta blockers either, primarily because they make me keel over every time I stand up, but also they only calm the physical symptoms, and the positive feedback loop that some people get from them doesn't work for me.
Pregabalin helped a little, but I was getting fed up of injuring myself as I lost whatever meagre amount of physical coordination I might have previously had, and quit it after I twisted my ankle so badly on a run that I had to call my partner to drive over and pick me up off the pavement.
Antipsychotics kill my anxiety, along with my alertness, my intellect, my motivation, my curiosity, and my physical health. Doesn't matter whether it's trifluoperazine, haloperidol, risperidone, quetiapine or olanzapine, every one of them turns me into a placid, gormless lump of human flesh with some new and alarming serious physical disorder (some permanent).
Have you ever tried an antidepressant that isn't an SSRI/SNRI? There are so many other classes to try… some people get on well with mirtazapine for anxiety, I've heard. Or you could look into an MAOI, especially if there's any element of social anxiety? There's a small group of people with social anxiety (and another small group of those with depression, especially atypical depression) who do really well on phenelzine, one of the MAOIs. Or there's the tricyclics — some people who SSRIs have failed do well on those. Or there's several novel antidepressants been released in recent years.
Some psychiatrists are so bloody unadventurous 🙄
I'm guessing if you've been offered ECT then you've already been offered relevant talking therapies, but it's always worth looking into a refresher if they've been of any help at all in the past. And if they didn't help in the past, it's always possible things could be different this time round — different circumstances, different therapist, maybe different approach (though for OCD it would almost always be a similar modality).