Yes, that's quite a significant decrease in density that you have experienced (although 'less than 25%' looks very much exaggerated). You went from 'great hair, regardless of your age' to 'good hair for your age'. Some guys - i am one of them - seem to have great hair until their late 30's, before heavy shedding and rapid loss of density sets in.
You have said it before: all that you want is the shedding and the loss of density to stop. If you could sign for this (or slightly worse) hair at 55, you'd be a fool not to do it. In other words, this would be your goal: slowing it down. This has been said many, many times before, too: your best course would be to ditch virtually all the treatments you're on and evaluate in a year from now. And try to calm down, of course. That is the hardest part, i can imagine.
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@Ourkes says: a therapist would be a very good idea. You're wasting these precious early middle aged years, in which most men slowly start to learn to live with the loss of their youth. What else can we do? Tormenting yourself like this, it's not worth it.