Hi there, I have also been getting migraines from about the age of 12/13 - I am now 20.
Internationally the best - and cheapest - method is to take aspirin as soon as the migraine starts (when you start getting the visual disturbances, even before you start feeling pain) and also to take an anti-emetic (medicine for nausea).
Unfortunately I can't advise you on the exact medicine brand or dosage since I'm not a doctor (yet) and also I bet we live in different countries. Your mom or dad will know which aspirin and nausea meds you can take.
If those don't help, you could ask your doctor to prescribe some prophylactic drugs for you, but he will first want to test some other therapies.
Also, when you get a migraine you should go to bed in a dark room and try to sleep for at least an hour.