What can i do if my period was 4 days late my test was negative, could i still be pregnant?

Maybe, retest in a : Few days. Reasons for missed/late periods: low body wt, 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 (polycystic ovary syndrome or asherman’s syndrome). #1 reason is pregnancy.