Who are you

How did you behave in the environment you occupied? From here, unless massive transcription or DNA realignment and/or huge intra-enviro changes, that is who you are. Obviously, genetic and/or environment are functions of time and thus we see a moving target, it still the best guess I can think of. Noted weaknesses are the measuring sticks.

Pleasure vs happiness

Pleasure can be defined as things that feel good at present time t or within hours. Good food, mind altering drugs, sex, massages, itching, etc. are examples. They rarely lead to fulfillment and some pleasures often lead to despair. The problems pleasure can bring are the disregard for temperance (doing activity which leads to doing more of the activity), moderation (over drinking) , social norms and one's conscience.. Over indulging with drugs or foods can and do lead to un-fulfillment.. Sex with prostitutes, although pleasurable often leads to moral decay. Cocaine and other chemicals are pleasurable but can lead to addiction(wanting the chemical above health, harm to others or any moral fabric that the individual holds) to the imprudent or careless. Often going against society's mores leads to shame or strengthens disillusionment.
Happiness is pleasurable but the reverse may not be so. Happiness is often but not always the completion of one's goals. . This can be demonstrated by the example of building. physical labour is an unpleasurable event. The body fights the unnatural urge to expend energy for non sympathetic events. The pleasure comes when the building takes form. The happiness is the completion achieved through the goal achieved even through adversity.The virtue of adversity is fortitude; pushing through the adversity of pain to master the challenge