Hi Hapylory. Welcome aboard! That's a great time for 5K and you should feel mightily pleased with yourself.
Have a look at the "girls running" thread a bit further down this forum list - it's relevant to you.
How much you should be running depends a lot on where you are with your growth and development and maturity. Some 14-year-old girls are adult sized, have finished puberty and are would be psychologically capable of full-time work or starting a family. Others are still little girls with a lot of growing to do. If you're a strapping lass whose periods have started and who is as tall as her teachers, you'll be able to train harder than someone who is four foot three and plays with Barbie dolls.
Which is a long way of saying "it's difficult to be sure without knowing a bit more about you".
Someone who really COULD help you is the juniors' coach at a running club. Do you have a club near you that you could go to? A goos PE teacher might be a great source of advice too, although not all of them have the energy to go beyond the curriculum.
Look forward to hearing more from you.
Cheers, V-rap.