My period has stopped for a bit, how do I get it back?

It will come back when its ready. Often when periods begin you do not ovulate, ovulation is the key to regularity in the cycle. Anovualtory cycles (which is cycles where you do not ovulate) are irregular and many many girls have these when they start getting periods. I had irregular periods for about 5 years until they settled into a pattern. Keep some spare protection in your bag or you may like to wear a pantyliner while you wait for the next period to come. Look out for sore boobs, a change in your regular discharge and irritable grumpy moods, headaches too for some girls.