From what I've read, your female is too young and you should wait before trying to breed this pair.
A female cockatiel should ideally be about 2 years old and a male at least 18 months old. Letting them breed too young is dangerous for the female, and increases the chances that the eggs will not hatch or that the parents won’t feed the chicks properly or they might even reject and try to kill the chicks. First time parents are also more likely to experience problems. Ideally, it is better to pair up an inexperienced bird with a bird who has parenting experience, so the older bird can help teach good parenting skills to the younger one. If both parents are inexperienced and also too young, a lot can go wrong.
Do you have previous experience breeding parrots? Is there anyone who you can ask for help to teach you how to hand-feed baby parrots? Having an experienced mentor is quite valuable. If you don't have a mentor, your avian vet should be able to show you how to hand-feed safely. Be sure to get the supplies and training BEFORE you need them. There won't be any time to wait if you need to rescue a rejected or malnourished chick.
Also, do you know if your cockatiels were hand-raised or parent-raised?
For now, I recommend patience and research. Your birds are too young, so you have six months to prepare. Also, please be aware that cockatiels will lay eggs and try to breed when they are too young to be parents. They are physically able to breed at just 9-12 months, but early egg-laying places the female at increased risk of egg-binding. As a breeder, you need to make the best choice for the health of your birds and their offspring, so please consider removing any nestboxes and not encouraging them to breed until the female is fully mature.
