My 9year old has started developing breast, is the eny medication to stop it. L feel it's toosoon for her?

Breasts at young age. No medication. Would not not interfere with mother nature, let it take its course. Best to discuss, educate, and advise her.
Normal. It is normal for a 9 year old girl to develop breasts at this time. Normal age of menstruation can be anywhere from age 8-16, and breast development typically starts about 2 years before menstruation. She does not need any medication to interrupt her normal puberty changes. This is a good time for you to talk to your daughter about bodily changes with puberty.