Unsolicited advice but...

Whenever I hear treatment resistant depression and it's someone who has been through the system for a long time and they've played antidepressant roulette so many times that the doctors just kinda shrug instead of having ideas for where to go next with treatment, I always encourage people to consider stuff that's somewhat off the beaten path.

Adult ADHD is typically where hyperactive traits from childhood, if they existed much at all, tend to turn into inattentive traits. Not always and not 100% but I'll spare you my idle hypothesising about why that might be. The important thing in this is that ADHD and especially the inattentive traits can often resemble TRD.

For very complicated reasons, autism can also end up resembling TRD especially in adults.

This next part is armchair expert stuff but I have a suspicion that the overlap between TRD and catatonia is much higher than is recognised in mainstream psychiatry and I'm staking this claim on the fact that the symptoms and most effective treatments for both have a major overlap.

I also think that it's worth starting from a clean slate with regards to symptoms and mapping out what they are in an objective fashion while withholding interpretation to try and identify if there's any outlying symptoms that are indicative of an underlying condition which has gotten swept up into the TRD diagnosis or a condition which has gone completely unexamined. I guess what I'm trying to say here is that it's really common for long-haulers to just attribute symptoms to TRD immediately without a critical assessment of whether this is accurate, and often this is something that is imparted to the person by the attitude of experts who treat them. Sometimes going over things with a fresh perspective can yield new options for treatment or symptom management that haven't been considered yet. Sometimes the "small" symptoms that you just deal with or ignore can actually be more central to the condition(s) than you realise and because you're so busy trying to manage the "big" stuff (or perhaps it's better to think of this as downstream symptoms), you never find the opportunity to examine the "small" symptoms or to treat them which can sometimes be the key to achieving better outcomes. Sometimes you have the interplay of more than one condition simultaneously which introduces complexity in terms of diagnosis, treatment, and management that does not exist for a solitary condition.

This is even more important when you start bringing in physical symptoms too, as mental health generally gets treated as its own discrete matter rather than looking at things in a (ugh) holistic sense. Not like crystals and chakras holistic sense though. You get what I mean.

Is it possible that you've got TRD due to the luck of the draw - a shit childhood, unfavourable living conditions, your particular neurochemical makeup, stuff to do with brain physiology like your particular development or taking a knock to the head at some point that has just turned out badly due to misfortune? This kind of thing is absolutely a possibility.

But I'd urge you not to let doctors just write you off and consign you to the too-hard basket and especially not to take that on board yourself. Even if you've exhausted all your treatment options, which is actually rarely the case in reality, this can indicate that the model of treatment itself is wrong and not that you're truly at a dead end.

I'm going to talk personally here as an analogy. I'm asthmatic. I'm also unfit because my mental health has been absolute garbage in the past couple of years in particular so it's been a matter of survival taking precedence over my physical fitness. Sucks, but that's life.

Imagine if I looked at being unfit through the lens of asthma - superficially the symptoms line up and you could make a decent case for why it's asthma. But imagine if I was operating under the idea that what I was experiencing was all just a case of poorly managed asthma or severe asthma. Maybe the argument for why this is right is convincing because, at least some of the time, my symptoms respond to asthma medication. But maybe I start avoiding exercise because I'm worried about it aggravating my asthma symptoms or triggering an asthma attack - by operating under a false paradigm or an inaccurate application of the paradigm (Yes, I'm asthmatic but no, that doesn't mean that every time I'm out of breath that therefore it's asthma) you can conceal what's really going on or you might even follow treatment/symptom management which aggravates the underlying cause (e.g. experiencing breathlessness -> avoid exercise -> become more unfit -> experience being breathless more often).

Am I telling you that your diagnosis is incorrect or that how you're treating it is actually making the symptoms worse? Fuck no - I don't know the first thing about your situation.

Am I telling you that your symptoms—all of your symptoms—are valid and deserve to be treated with the highest levels of respect, consideration, and care and that you're allowed to think about your condition as being "treatment-unexplored depression", and that it's better to give up hope for the diagnosis being accurate than it is to give up hope that the condition itself is treatable and that there might be options for better symptom management? Fuck yes, absolutely.