How can I get A stars in my GCSE (Exams)?

I really want to get A*'s in my GCSE (exams), my mother is sick, my father is at work all day...I take care of MYSELF literally. I live with my bro and my 2 younger sis. I'm in charge of the house and everything I can't handle it anymore...I'm so stressed out, my exams are next week literally. I'm in year 10! And I want to pass with A's to make my family proud....I revise hard, I try hard in school yet I need that something which will boost me up to A's because right now I am a B/C student. Please help, any ideas on how to get A's in my exams....I have just three days left to prepare until my FIRST exam...urgh I feel so stupid, I always start to cry and feel so incapable. My mind tells me that I am capable but I just need help...please help me!