When i watch porn my clitoris area starts pulsing for 2-5 seconds. i don't touch myself but i do hold my breath. i cant go farther, is this an orgasm?

Not quite: It's not at all uncommon to become aroused while watching porn and to have that localized sensation in your clitoral area. If you were actually having an orgasm, you would be feeling an almost indescribable release of an intense sort of a pleasurable "pressure" in your uterine/clitoral area. If you were to stimulate yourself, you may likely go that little step farther and experience a full orgasm.

Likely,: There are 3 phases involved including arousal, orgasm and resolution. The arousal period allows for engorgement of the clitoris and stimuli to nerves followed by the orgasm. In many females they are closely related and not truly seperate. If after the 5 seconds there is a calming period or relaxation, this is the resolution phase and the previous reaction was an orgasm. It is all normal. Good luck