I feel for you so much as you face the overwhelming challenges that can come with mental health. It's incredibly hard when very few people seem to really understand or even want to.
Wondering if anyone in your life has congratulated you on constructively managing your mental health. It's a significant step when we seek professional help and definitely a step that deserves acknowledgement. Looking back to when I was in my depression, while some of my management strategies were questionable (alcohol), other strategies I'm very proud of. It's important to remember how well we're trying to manage under the circumstances. The circumstances can be incredibly challenging, more than those around us may imagine.
If association is based on how we relate to people, disassociation can sometimes be an indication of us not relating to them on some level. It's taken me years to master the ability to instantly detach from a person under certain circumstances. This began with some important questions, 'Why do I feel so hurt by this person? What's wrong with me, why am I so sensitive?' This can be a depressing process to go through (self questioning) until realising how valid the questions actually are at a deeper level. I found a few answers to be 'I feel hurt because what they've said or done is cruel, by my standards. I, myself, wouldn't do or say this to another'. The other question, 'I'm sensitive because I'm not insensitive. What's 'wrong' with me is that I'm tolerating perceived insensitivity or thoughtlessness'. Of course, this set off a chain reaction of questioning, with another significant question being 'Why am I tolerating the intolerable behaviour of others?' So, through this process, I've gained the ability to either emotionally detach from behaviour I find intolerable or I question those whose behavior is highly questionable. Such a process has been a natural self-esteem booster. I also discovered, if I don't appoint someone a role they simply can't fill, I don't face the disappointment process.
Emotion is a very physical experience. Can be hard to feel emotion when we're detached or exhausted. Can be easy to feel emotion when someone/something is positively exciting every cell in our body or when our mind and nervous system go into hyperactivity mode, such as with anger, fear or a rise to much needed courage.
Sometimes there's good reason for the sense of disassociation toward others. Continue to question on your quest of self understanding.