Is it too late to get 9s?

Tomorrow is my last day of core subjects mock exams and I am working at grades 8-9 for English but for science and maths I keep getting 5-6s but for the real thing I really need 9s

I'm in top sets and doing higher for all but whilst I understand grade 9 maths, I rarely get enough correct for even a 7 and for science I struggle to remember the facts, practicals and what to do for the complicated science maths questions

For my other subjects I have another 9 but the rest are always 6 or 7 (seriously)

My school doesn't have a 6th form, so I absolutely have to have the top grades in order to outcompete and get selected to be one of the few that 6th forms take in from other schools

My exams start in just over 2 months and I'm scared I'm going to mess up once again