I've never really had a regular period?!

I've definitely heard that stress can do that, but it would take a lot of stress to make your hormones that out of whack for that long. You would be a complete mess by now. But then again, your body may be more sensitive to stress hormones than others. But sometimes it's for a medical reason, and sometimes it's just random for some girls. It's all really vague because it's not completely the same for any two women. I have friend who used to get hers at the same time as me, even when I was on birth control and she wasn't, she was just perfectly regular, but then she randomly started skipping it periodically. I would see a doctor to rule out stress or medical problems, and if it's a big hassle you might want to consider a hormonal birth control method to regulate them. Even just the minipill can regulate periods.

I think this is pretty normal for a girl your age. As you get older it may start to even out and you will get your period on time. I found doing exercises everyday helped mine become normal. Try to eat healthy too. If it keeps up you could be checked out by a gynecologist to be sure everything is okay. Also, birth control pills could help this but should be avoided unless this really bothers you.

Sometimes it's not regular for a medical reason. But for some woman it's always random.

It is just how your body functions, you should go on a birth control because it helps regulate periods and reduces cramps, bloating, and acne! Plus plus plus :)