Hmm....quite the conundrum.
Alex,
Mum is seriously looking out for your best interest, and there's no other woman on the planet that can even come close to Mum. Mum's are the BEST
Now, regarding your question, it's really not easy to give you a black and white answer. Everyone else has given you good advice though.
I remember when I was your age wanting to fly heavy iron internationally, going to the airport to take pics or watch the planes takeoff and land, wondering whether I'd ever make it....
BYALPHAINDIA's advice of having a plan B, C, D or as many as you want is very good. The reality is that the airline industry is such that nothing is certain for sure. To give you an example, legacy carriers in the U.S. such as the mighty Pan Am, TWA, Braniff, Eastern - nobody in their wildest dreams would ever thought that one day they'd be gone. Just as Ansett in Australia - Sir Reginal Ansett is definitely rolling in his grave.
During 9/11 (2001), who would have thought the mighty United Airlines along with every other carrier would be laying off pilots. Having come from a previous US major, if I had stayed where I was, I too would have been "out on the street".
Azamat69 has mentioned an important statement that MANY do not realise because all they see is us wearing our uniforms, our epaulettes, our hats, and we bore holes in the sky.
It wont be easy, dont let anyone tell you otherwise, but i think thats what makes the pilot breed so unique!!
Indeed, a VERY true statement. It is not easy at all. The whole process is challenging on a personal level and just like anything else in life, there is a "game playing" role that you'll need to learn as you progress throughout the career. Part of the process is also abit of luck, in the sense of "being at the right place at the right time".
I've been flying professionally for 24 years and I can count on one hand those that "had it easy" from Day 1, starting as a Student pilot to flying widebodies. It is not an easy career to attain, but certainly, the rewards are worth the road to success.
My thoughts (for what it's worth) are....
If you truly want to become an airline pilot, go for it. Study hard, and stay in the books because that's what your entire career will be - constant study. Your study habits are formed now whilst you are in high school.
As well, DO HAVE A BACKUP PLAN incase (God forbid) something happens such as medically unfit to fly, or Company goes bankrupt. I worked for 2 of those now bankrupt Companies. At least you'll know that you have a means of paying your bills whilst you search for another flying job.
Whatever you decide, best of luck with all your endeavours and future. I hope to hear you someday on the airwaves at FL390