I work long hours and sitting down on a computer and this was the 1st month i don't know if my body it's shocked or what i have pain in my stomach and i haven't received my period i'm just so confused, and i do have period pains but no periods?

Fairly common: Irregular menstrual bleeding is fairly common. It is usually caused by fluctuations in hormones. Hormone levels can be affected by stress, weight gain/loss, increased exercise, lack of sleep, or pregnancy. Other causes can include ovarian/uterine problems such as ovarian cysts, adenomyosis or fibroids. If the lack of periods persists, talk to your Gyn Dr for a full evaluation.