How should one stop stressing about studies, be optimistic especially when you have your parents and teachers pressure on you that you have to get good grades. And is there any dua which will help me while I am studying?

Try your best and also explain to your parents you are trying hard. Use the dua that Allah gave the prophet (s) in the Quran 20:114 Rabbi zidnee ‘ilmaa (my Lord increase my knowledge).