Should i breed my cockatiels?

Hi I have a male and female cockatiel and I'm not sure of the ages they both have moulted and I know one is a male and one is a female and the male has showin signs of sexual maturity but the female hasn't but when the male preens her she loves it and when he stops she chirps for more I don't know if I should let them breed or not cuz I don't know their exact age? What should I do?