If you don't mind my asking then... How was she still ovulating while pregnant? And how did she not miscarry? A menstrual cycle occurs roughly 10-14 days after a female ovulates. It works in a particular way.. Each month your body prepares for a potential pregnancy, by the lining in your uterus thickening and your hormones changing. After so many days your ovaries release an egg which starts its journey down your tubes. After roughly 12-24 hours, if its not fertilized, it dissolves. Your body then prepares to flush out the tissue and roughly 10-14 days after ovulation does so in the form of your menstrual cycle. If it is fertilized it travels down into your uterus and implants into the uterine lining. If you had a true menstrual cycle when pregnant you would shed this lining, and with it, the fertilized egg.
It IS possible to bleed and sometimes bleed like a period but it is NOT a true period.
I agree with your first statement clysta but I beg to differ with your second statement. My mom had a period every month of one of her pregnancies but had to be constantly checked on. They sometimes happen together although rare. Anyway.. stress will only make things worse, it can cause phantom pains that your mind creates. I would test if you're worried, we can't tell you you're pregnant or not. It's just not a skill done over the internet...
It doesn't matter how old you are, age isn't any form of excuse. Children aren't just a causal 'oh well, being stupid is my thing' idea. It's a human life - do you work to support this child, do you pay your bills, your own shopping? Do you live on your own as well? If you don't, how do you expect to care for a newborn. Sex is NOT something to just play around with, it carries extremely serious consequences.
As for pregnancy, if you had a period.. No you wouldn't be pregnant. The two can not and do not happen together. Next time be more responsible