I’m so sorry that I am just now seeing your message and that no one has replied sooner. I really appreciate all that you shared, especially since, as you say, it may help those who read your story in future to know that they are not alone.
I imagine the loss you are experiencing is excruciatingly painful but also probably less recognised by those around you than if your son was no longer living. This is known as disenfranchised grief and this type of loss can be particularly tricky as the griever is usually given fewer opportunities to talk about the grief they are experiencing.
It sounds like you are very resourceful and have come up with several strategies for boosting your mood and taking care of your mental health, which is both reassuring and positive. I would encourage you to keep doing all the things you listed and to lean on the healthy relationships you have in your life.
You may also like to read the Griefline resource on loneliness and isolation (https://griefline.org.au/resources/loneliness-and-isolation/) or relationship loss to help you cope with some of what you are feeling.
Please keep talking and hopefully others may be able to provide useful advice too.