I haven’t menstruated for two months. I had spotting last week but no sign of my period as yet. Two negative pregnancy tests.?

Hormonal imbalance. Menstrual irregularities are not uncommon and anovulatory cycle is a common cause. If you miss more than two periods it would be time to see your doctor. If you do not wish to be pregnant, use contraception all the time. You may consider implanted contraceptive or an IUD.
Consult this site for more information on this topic.
http://www.nichd.nih.gov/health/topics/menstruation/conditioninfo/Pages/causes.aspx
Practice safe sex, if you have sex.
Some thoughts... In a woman with regular periods, some causes of a late period include: excessive weight loss or gain, increased exercising, emotional stress, having an illness, traveling, medicines (like hormone pills), hormonal imbalances, etc… Seeing a doctor is a good idea if symptoms are persistent, recurring, or worrisome. Pregnancy is a cause of a missed period, but tests are accurate 3 weeks after sex.