Periods are very irregular when you start. Your PMS is due to hormone changes, not your period. Normally these changes happens just before your period but since you are not really menstruating yet, the hormones can affect you without you seeing any menstrual flow.

What you are describing is creamy cervical mucus. It means that your body is getting ready to ovulate. It goes from your period to dry to sticky to creamy to watery to raw egg white back to creamy to sticky to dry before starting with your period again. Not all women experience all these changes in cervical mucus but it is a sign of changing hormone levels.