Most probably you have short regular cycles.
The menstrual cycle is genetically and hormonally determined cycle in women reproductive system. Menstrual cycle is very specific and individual, and can range 24 days to 37 days. Duration is not so important but the regularity is very important. At the beginning cycles could be not regular – it is a period of development. Just remember – normal cycle is what is normal for your body.
Read more in http://www.menstrual-cycle.info
Be Healthy and Happy!