I know its happening tomorrow and it's way too late to say anything to change your mind either way but i still thought i'd jump in.
Fact is, you only live
once. You only get one shot at this, there is no going back in time. To borrow from the gaming world, there are no save points to go back to and there are no respawns. Once your life is over, it's game over man. It doesn't even matter if you believe in an afterlife or not because all the versions i've heard of are substantially different from this life.
There is a chance to do x or y later in a limited sense but you only have 80 years at it. The one life you get is too short and far too precious to get anything
but the best out of it just to make your parents more happy or to be slightly more wealthy.
I can't emphasise enough how much something like this needs to sink in for a person making a decision of your caliber,
you only live once.
Sure it might make your parents more happy but at what cost? They'll be able to live and adapt if you don't do medicine but if it is such a big trial for you and you are always wondering "what if", i say that sacrifice is far too large. Nothing is forever either, your parents will eventually no longer be around but you still could of wasted so much of your own life on a goal that wasn't yours.
One idea in philosophy is this thing called eternal recurrance or eternal return. The idea is you are forced to life this same life over and over and over again. The idea is, if you lived your life wrong, the torment will be far worse than even hell. You will constantly have the same regrets over and over, the same mistakes. If you wanted to be an artist but became a dentist instead, you will have to experience that let down and disappointing infinitely.
Few quotes ripped straight out of wikipedia (because i am lazy):
"
What, if some day or night a demon were to steal after you into your loneliest loneliness and say to you: 'This life as you now live it and have lived it, you will have to live once more and innumerable times more' ... Would you not throw yourself down and gnash your teeth and curse the demon who spoke thus? Or have you once experienced a tremendous moment when you would have answered him: 'You are a god and never have I heard anything more divine"
"
My formula for human greatness is amor fati: that one wants to have nothing different, not forward, not backward, not in all eternity. Not merely to bear the necessary, still less to conceal it—all idealism is mendaciousness before the necessary—but to love it"
Every chance to talk to a girl when you didn't, every time you could of worked harder or worked less and enjoyed more of life and didn't, every mistake, every regret, to be lived over and over an infinite amount of times. Sure sounds horrifying to me. The idea is you should life your life as if you had to experience it an infinite amount of times over, live your life as if you would change nothing if you could (which is the situation in the quote where he thanks the demon).
By deferring you're essentially delaying the decision and the associated anxiety, it's also a good choice but its essentially suspending judgment, sooner or later you'll have to choose one of the other two ways. By all means defer if you think it is best though but i am not sure if you will have a much better idea after a year off (of course you could just use a year off for other reasons to relax after all that hard work, volunteer, work, etc).
Sometimes though, theres the
right choice to make and then theres the
easy choice to make.
Massive kudos to you though for
having the balls to do something many want to do but few
actually do.
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Edit: I think as appianway pointed out and rightly so, is that you might be idealising education in the same way a lot of kids idealise med. I know its a tough thing to hear when its your passion and all but some of her suggestions are real good ones to take up too.