I know it’s hard not to compare yourself to you’re friends but remember, everyone is different. The average age for periods to start is 12 to 13 but anywhere from 11 to 16 years is normal. The white/clear stuff in your undies sounds like discharge which usually starts in the year leading to your first period. It is normal and is there to keep you healthy as it prevents infection, lubricates and makes it easy for sperm to reach your uterus when you are trying to have a baby. It can vary in colour from clear to white and can go from thin and watery to thick and gooey. If you have itching or stinging or your discharge is grey, green, frothy, smelly or thick, white and cheesy, see your GP.