My period is almost a week late and it's never late, i've took a pregnancy test and it keeps saying negative, i was thinking about waiting a week?

Can retest in 1 week: In a woman with regular periods, some causes of a late period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, medicines (like birth control pills), hormonal imbalances, etc… Seeing a doctor is a good idea if symptoms are persistent, recurring, or worrisome. Pregnancy is the common cause of a missed period, if sexually active.