I am pretty upset with myself for not doing well with my studies.
What do you think the reason for that is?
Yes, my parents and teachers always push me hard and I can't take constructive criticism.
I can understand why you are so hard on yourself and it's okay to be upset when you think you aren't performing up to standards. You could always ask for help if you are struggling. Maybe explaining to others that you are trying your best they might go a little easier on you.
I'm not a failure yet. I'll tell you when it happens.
Try not to be so hard on yourself. As long as you are giving your best effort than you should be content. Maybe try adjusting how you go about studying, or maybe try getting a tutor in the classes that are more difficult for you.