I need to improve

[mango1]

I have been playing piano for 11 years, since I was 5 years old.  However, I never practiced until about 2 years ago.  Like never ever, maybe 15 minutes twice a week.  I just kind of strolled through lessons.  So, I never really improved.  ABout 2 years ago I decided to start actually practicing, so I did level up somewhat.  Now, I am 16 and disappointed that I wasted so many years that I could have been really improving.  I try to practice every day now, but with a lot of schoolwork I often can't fit practicing in.  Anyway, I am in Royal Conservatory book 8.  So, at that level how long should I be practicing per day?  And do you recommend any pieces that I could try?  I am trying to become more advanced, and I want some interesting but challenging pieces that will help me improve.

[mango1]

would Mozart Sonata K 545 be manageable do you think?

[roseamelia]

You could do that one, you should probably practice for about 30 minutes or maybe an hour or so. Try that it should be long enough practice for you.