You have been with her a long time. How does she handle you mood changes? Does she give you the space you need when the depression comes and you want to crawl in a hole? Those are the kind of things you have look at, can she deal with your mental illness?

You might want to go to counseling to see why this fear is clouding you feelings.

And yes, I have doubts about a lot of things I do, and talk myself out of what it is when I'm depressed. The one I have to watch is decisions I make when I'm manic. My mind can get me in a lot of trouble. But you are talking about someone you have been with for 4 1/2 years. Has the relationship been a good one so far. Good luck what ever you chose.