17 days overdue for my cycle. nausea n vomiting. lower stomach n back pain. but no other preg signs tho. been under sum stress. prego or stress?

Possibly: Stress and pregnancy can certainly both cause a missed period.I would try a home pregnancy test and if not pregnant see your doctor for more answers. Good luck.

Could be: It could be either since both can cause your symptoms. If you are having unprotected intercourse pregnancy is always a possibility. Do a pregnancy test to know for sure and, if it is negative and your period still hasn't started, repeat it in 3-5 days. If you don't want to be pregnant, reduce your stress by starting a reliable method of contraception. Best wishes and good luck. Hope this helps.