I was stressed about my health condition, stressed at school, i sleep late at night, i never had sexual interaction but i missed my period in 3 months already. are they connected? could stress caused my period to miss that long? i use to be regular?

Many normal women occasionally skip a cycle or two. Those who are underweight may also stop menses. You no doubt have stress but I would not blame if for 3 months of menses cessation. Some docs will offer meds to trigger a cycle if your pregnancy test is negative and you have gone this long without.

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