Stress can cause missed periods. Other causes can be from medications, eating disorders, illness, weight loss/weight gain, drugs, birth control, and issues with your ovaries such as polycystic ovarian syndrome.
Three periods is a lot to miss. You should make an appointment with a gynecologist for a check-up, pap smear, and pelvic exam. It could be something as simple as stress, but it could also be something very serious with your ovaries as well. You should make an appointment as soon as possible to make sure everything is okay.
I had ovarian cysts when I was a virgin at 13 years old and was rushed to the Emergency Room. I had to start taking birth control to regulate my periods and to prevent the cysts.
Here's a link to possible reasons for missed periods:
http://women.webmd.com/tc/missed-or-irregular-periods-topic-overview
Hi there and welcome. Well, yes. Stress can be part of delayed and abnormal periods. I actually had cycles that were three months and longer for a period of time in my late 20's due to a slow thyroid. I would get pms symtpoms including the bloating during that time and it was hard! I also had a low level of depression, dry skin, etc.
I would go see your doctor about this to figure out what is going on. since you know you aren't pregnant, obviously your hormones are out of sync. Finding out why might give you piece of mind and then perhaps they can figure out what to do to make you regular again.
My issue self regulated and 'fixed itself' after a year. good luck