is a bp of 100/60 low enough to produce symtoms of low blood pressure ?

Is that your BP when you are dizzy or a pressure from when you are feeling ok? Do you get dizzy upon standing? Young people often times have orthostatic hypotension which means their blood pressure drops upon standing and it can make you dizzy and light headed. There are also other causes for dizziness so I'd suggest talking with your doctor about it.

Yes. If your BP is low enough sometimes you get dizzy, especially when standing up or doing a similar movement. 100/60 isn't outrageous, however your BP is not always the same -- if it's that when you happen to measure it, it may be lower at other times.

However no one can say why you get dizzy, because we don't have enough info. You're lightweight -- are you anorexic or starving? Or are you just naturally skinny? Do you eat enough? Do you eat healthy? Etc etc.

You should weigh at least 102 pounds. It could be low blood sugar from not eating enough. 100/60 is not particularly low. How low is it when you are having symptoms. Do you have a blood pressure monitor? Blood pressure can vary quite a bit over the day.

Low blood pressure causes Faulty nutrition, Malnutrition The most important cause of low blood pressure is faulty nutrition. It makes the tissues forming the walls of the blood vessels over-relaxed, and flabby or streched. This results in less supply of oxygen and nutrients to the tissues. Malnutrition can result from a diet deficient in calories, proteins, vitamin C, or almost any one of the B vitamins. Loss of blood, slow internal bleeding Sometimes the blood pressure falls rapidly because of loss of blood. Low blood pressure may also develop gradually because of slow bleeding in the gastrointestinal tract, kidneys, or bladder. Emotional instability Emotional problems are a far more frequent cause of low blood pressure. To a lesser degree, prolonged disappointment and frustration may result in a subnormal blood pressure.