Period is 6 days late...i have taken 3 pregnancy tests, all of which have resulted in a clear negative...is there still a chance i could be pregnant?

Not likely: Three negative pregnancy tests attest to the answer.

Maybe - consider: repeating in 4 or 5 days if still no menses. Reasons for missed/late periods: low body weight, obesity, marked weight ^ or v, over-exercise, endurance athletics, breast-feeding, ^ stress, illness, eating disorders (bulimia or anorexia), anovulatory cycle (no egg released), travel, hormone irregularities, drug use, meds (i.e., birth control) or medical problems (i.e. PCOS). #1 reason is pregnancy.