Dear Curly,
My first thoughts are that if you've always had this, it is more likely ADD than bipolar as my feeling is that bipolar shows up later than ADD, although not necessarily. Do other people in your family have this?
If you are able to find work arounds for this, then maybe you do not need to seek med or other treatment. Still, you can let your medical professional team know about this as it helps them to have the whole picture.

I know someone who goes blank when other people are talking -- kind of takes a rest until it is his turn to talk.

When you sing in your head, are you any good? Do you run out of songs to sing? I can only remember a handful of songs and then I get bored with myself.

M