Im a 17 year old and like you i am determined to succeed to be a pilot or WSO, i will aim for the raf and if i dont get in because of a asthma related problem i will probably aim for the navy as ive found it can be more lenient especially in my situation. But ive been told by many people, to become navy aircrew you have to want to become a naval officer first whereas the raf is designed solely to fly which is something you might want to consider. Good luck!