You are not alone with this questions! There are of many others who want to know the same thing. There is an answer but first lets ask why not
expect a lot from you? The scripture says that we are wonderfully and
fearfully made.

Psalm 139:14 New International Version (NIV)
14 I praise you because I am fearfully and wonderfully made;
your works are wonderful, I know that full well.

But as to your “question” Those who are placing the pressure on you to
perform at a higher level are simply attempting to pull out the greatness that they know is within you. Of course I am speaking of parents, teachers, and athletic leaders. If you are getting pressure to be someone you are not from a boy friend or girl friend it is an all together different issue and you need to set the boundaries on who has the right to develop your life.
My suggestion would be to take a step back from all the heavy thinking and prioritize the influences.
1. First Thank God he is always the main priority.
2. Give thanks for those who are attempting to develop your life and bring maturity into it.
3. Now look at what is expected of you and determine how important it is to those who are for you in life and on the side of your love and happiness. There must be some reasons it is necessary if your parents are attempting to have it influence you.
I hope this helps but it can be a much deeper subject depending on the
issues involved. For more information you can email and ask for more on this subject leaving some details. Thanks and God bless.