Yeah my parents are like that too sometimes and it can get frustrating at time too.
I really don't understand their reason for that, maybe they just want to push us the hardest so things won't look so hard when we handle them.
My parents are the same way, I wish they would tell me more often how much they appreciate me. Just once in while would really help, but recently I had a talk with my dad and he told me that even though he doesn't tell me how proud he is of me doesn't mean that his not proud of everything i do. Maybe your parents are the same.
I am going to warn you it will take a long time. XD
I might write another one around the month my friend killed himself. Otherwise I have a pretty boring life.