Also, I'm a year younger than you and fear dying a traumatic death, aging alone, dying alone, etc. I may not experience as severe of symptoms as you, but have you also considered writing down some details about your systems and where you think those thoughts and feelings originated from? This way, you can help your treatment team help you better.
For example, it sounds like you've experienced medical traumas in the past. As a child, I had experienced medical traumas repeatedly, in addition to physical abuse, sexual abuse, emotional abuse, emotional neglect, witnessing domestic violence, witnessing natural disasters, experiencing homelessness and poverty, experiencing school bullying, experiencing racial traumas, and more. All of those things add up over the years whenever I got retraumatized in hospital settings, therapeutic settings, workplace settings, and relational settings.
Although Cognitive Behavioral Therapy helped me to see where the sources of my triggers might have stemmed from, and what my immediate reactions were (my automatic thoughts coupled with my automatic feelings to both the situation and my automatic thoughts), I still struggled with the "coping skills" to cognitively restructure that which was "distorted." Why? Because ongoing trauma triggers, such as pandemics, what's in the news, racial traumas, and relational traumas in intimate partner violence/domestic violence is not in the past, and is very much real - not a distortion. Until I sought help from someone who understood present-day traumas that are ongoing, I felt like my laments and fears were minimized, which invalidated my reasons for treatment.
I then reevaluated what I wanted out of treatment. It wasn't just for my painful feelings and fears to go away, but it was also for a sense of justice when I never received any justice in real life. It was for receiving validation and a "this isn't right what happened to you and what continues to happen to you."
As for medical traumas, witnessing a disabled parent or sibling or extended family die, or witnessing them suffering long-term before their death, might be a vicarious medical trauma in the past coupled with a form of child emotional neglect (the lack of explaining to the child that the child should not have been adultified, parentified, or exposed to those situations without comfort and good explanations from the parents). Additionally, if you were constantly in and out of the hospital yourself as a child (as I was and my sister was), then all the things you experienced and/or witnessed may be bringing about the triggers in today's traumatic pandemic, today's ageism, and today's ableism. As harmful as racial trauma is, so are age-based traumas and disability-based traumas. People stigmatize the disabled, the mentally ill, the obese (which can stem from both physiological metabolic disorders related to hormones as well as from neurological and/or psychological disorders, including sleep-wake disorders), and the elderly. They devalue them in society, and such traumas are ongoing and valid.
If that is anything remotely comforting for you to know, then I hope this helps validate both your current please for feeling at your wits end, but also for the lack of justice that ensues and depresses as well as oppresses minorities in these particular classes. As we age, we are more prone to stigma, mental illness, physical disabilities, obesity, and ageism. Age therefore becomes somewhat of a depressing notion, instead of a noble one of survival, positive accomplishments (e.g., establishing a legacy to leave behind), etc. When you've been alone most of your life, the world becomes a scarier place because of your lack of support and protection through that support. Being alone makes us more vulnerable - no matter what we're struggling with, so it comes as no surprise that our fears become heightened when alone.
Finding support from others who struggle similarly as you will help a little - maybe not a lot, but definitely a little. Having online contacts here might not cure what you're going through, but at least it is a step in the right direction.
Finding support through your primary care doctor, your psychiatrist, your psychotherapist, and/or a neurologist/neuroscientist will also be helpful. Even if they keep trying different meds and treatments, and even if that gets frustrating and retraumatizing at times, it's still a step in the right direction toward managing your symptoms. You pick small tools here and there that work, and you chuck the stuff that doesn't. When nothing works, you make a list of things you've tried, and you write down why it didn't work, what your reactions were, what you were trying to treat or your clinicians were trying to treat, and why you don't benefit from it. Making this list out will not only help you identify what hasn't worked and why, but it will also help your treatment team to also consider what hasn't worked and why.
There might be ongoing research out there for treatment-resistant depression, but it also sounds like you have specific phobias, anxiety, PTSD, and a history of some sort of medical trauma. It's the "medical trauma" that often gets negated by society, in particular those who have been desensitized by medical traumas when they are themselves experiencing vicarious trauma through their jobs - like doctors, nurses, paramedics, ICU staff, ER staff, and even psychotherapists, psychiatrists, etc. If they've been desensitized and don't have your disorder, how can they possibly address or even validate medical traumas? But it is real and a thing.
So look into all that, and if you have the energy, make a list to help you help others with helping you better.
I hope this makes sense.
Hang in there.