firstly you have to find out why is your daughter having anemia
( low ferritin level ) . i think it is mostly due to her periods. but here are chances of other causes also like worm infestation which is common at this age. what you need to do is deworm her. ask your doctor and he will give medicine after examining her.
now coming to the vomiting
part ,anemia and iron tablets both can cause vomiting.
iron tablets cause gastric irritation and vomiting ,even constipation
. it should be taken after food only and dose should be divided correctly. in case she is having too much vomiting go to your doctor and you can ask him to switch to iron injections. but iron injections have different side effects like staining of skin allergic reaction
inform your present doctor about the vomiting and he will guide you