Missed 2 periods. last period feb 11. took blood test 3 weeks after march 11, neg. took urine test at home 7x negative. currently taking medroxyproges acetate 5mg for 10 days. having shoulder tip pain can it be ectopic pregnancy ?

Urine and blood pregnancy tests should be positive in ectopic pregnancy but an ultrasound is needed to see if it's ectopic. Despite your many negative pregnancy tests an ultrasound would give you peace of mind. Your physician or gynecologist would have to agree to order one for you,however.

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. http://www.nichd.nih.gov/health/topics/menstruation/conditioninfo/Pages/causes.aspx