My period was really late in april an the i didn't have a period in may iv took test but it say i'm not pregnant is it possible i could still be pregna?

Unlikely: Home pregnancy tests, if read correctly, are very accurate.

Possible reasons: Reasons for missed /late periods: low body weight, obesity, marked weight gain or loss, over-exercise such as in endurance athletes, breast-feeding, stress, illness, eating disorders (bulimia or anorexia), travel, hormone irregularities, drug use, medications (i.e., birth control) or med problem (polycystic ovary syndrome or Asherman’s syndrome. #1 reason for missed period is pregnancy.