I spent years trying to figure that out - it was hard to separate all the different sides of myself and figure out the CORE of me.

Take a look at the things you like ALL the time. What traits do you have ALL the time? Even when depresseed, there are still always the things that I WISH I was feeling good enough to be doing.

For example, some of the things that are at my core:
- I always enjoy reading
- I always like to make up stories
- I have a good sense of humour
- I will go just about anywhere if it's what my friends want to do
- I will always park my butt down and listen to a friend if they're upset
- I am always a hardworker
- I am very stubborn
- I have a strong sense of fairness

There's lots of others, but those are just a sample. Even when I'm depressed, those things are STILL there to some degree. They're me.

Things that I do which aren't ALWAYS me, but are part of my depressions/ups:
- lethargic
- not following routines
- socially a hermit
- more reckless with my safety
- irritated/snappish
- wishing I could give up
- being unfocused

Those are all me still.... but they're not my "normal" self as they aren't at the core of who I am. They're traits of mine that only show up during a depression or up. And even during those - they don't ALWAYS make an appearance.

I'm not sure if that helps at all... but it's how I sorted that out for myself.