I need advise on wether to keep playing the piano or not...?

i have been playing the piano for around two years and my piano teacher has told me that i am extremly talented. i recently got a $20,000 grande piano on his advise and it all seemed to be going well. unfortunatly i am having second thoughts as i wanted to become a concert pianist but am worried that i wont make it. i am constatantly pushing myself to play harder pieces such as brahms first hungarion dance,chopins fantasie impromtpu and prelude in Bb minor( also by chopin) as i love music but my technique and posture isnt very good and while i can play them it leaves me with a sore back and forearms. if i dont play harder peices and stick to the easier peices i get in my lesson, i end up becoming tired of playing because, while i cant play them perfectly, they arent challenging my musical abilities. i dont know wether i should just give in and quit piano.