i have gone through similar situation and i too might have spd and never been diagnosed. all that you say here resonates with me. for me other things are okay, but "I don't have a self or personality of my own" is something of a fundamental problem for me. because of this, when i interact with anyone, i tend to adjust to how they are. if i interact individually with person A and then individually with person B, the most confusing part is interacting with A and B together. confusing for people i mean and people think, oh this is not how you are. not able to dance and disconnection from body is another sad thing. i am 41 now and with time i think i have improved. i share more with people and care less about what people think of me. i hope it will improve for you.