personality, disposition, identity, oh my!

Interjections show emotion or excitement, Hallelujah! Drat! I am frustrated! I am trying to figure out this proposal and the problem is my lack of knowledge of the literature. I am fairly certain that the term I will use is "personality" but the terms "disposition" and identity keep cropping up... only in graduate school would a person have to figure out the difference between these three terms which essentially define how a person thinks and acts and why....

so here is the dictionary....

Personality

1. The quality or condition of being a person.
2. The totality of qualities and traits, as of character or behavior, that are peculiar to a specific person.
3. The pattern of collective character, behavioral, temperamental, emotional, and mental traits of a person: Though their personalities differed, they got along as friends.

Identity

1. The state or fact of remaining the same one or ones, as under varying aspects or conditions: The identity of the fingerprints on the gun with those on file provided evidence that he was the killer.
2. The condition of being oneself or itself, and not another: He doubted his own identity.
3. Condition or character as to who a person or what a thing is: a case of mistaken identity.
4. The state or fact of being the same one as described.
5. The sense of self, providing sameness and continuity in personality over time and sometimes disturbed in mental illnesses, as schizophrenia.

Disposition

1. The predominant or prevailing tendency of one's spirits; natural mental and emotional outlook or mood; characteristic attitude: a girl with a pleasant disposition.
2. State of mind regarding something; inclination: a disposition to gamble.

The only problem with relying on the dictionary is that in the Academic community folks like to re-invent (and invent) words for their own use.

For instance, a more accepted definition for Identity would include some notion of performance and relate to how in my identity as mother I am a different than in my identity as a graduate student. But it gets all muddy because who I am as a mother influences who I am as a scholar and vice versa. And all of that is influenced by my social position in society... white, well-educated, affluent. And my underlying beliefs ... one who follows Christ.

I can hardly figure this out for myself... is this a fool's errand for my research?