When your identity constantly changes, how the hell am I supposed to know when something is right and when something's wrong?

Lately, for instance, I've been isolating myself more and more from my friends because I feel like they aren't "close" to me and that I'm just being used by them so they can have a fun drinking buddy or whatever, whereas I need more reliable friendships than that.  How do I know if this is actually right or if I'm supposed to give them a pass and accept them as more acquaintances rather than friends? Am I over sensitive a la borderline irrationality or do I truly not want them in my life?

This is something that spreads across all areas of my life, too -- from which job I'm holding, who I'm dating, which friends I have. It constantly changes and I never know if I'm irrational or actually "being true to myself" because it changes constantly.