hey! im a year 13 student, i think u will be absolutely fine please dont worry too much
4 months is more than enough, especially considering how many hours ur managing to do, thats great well done
heres some stuff i did that i think may help for the subjects u mentioned:
maths: maths genie/pmt do past paper questions and refer to the mark scheme, they pretty much use the same kind of questions each year but just change them up a bit so memorise the answer techniques
biology: save my exams is good, but you should try out pmt, it has a lot of revision notes for the topics there but i promisie you theres nothing better than just practising past exam questions, its the same as what i said for maths (also watch freesciencelessons for stuff u dont understand hes great)
english: this may not work for you but I think for english doing past paper questions isnt as helpful, instead, you can make notes on the books for english lit, memorise points you think you can explain well, for english language practise exam question structure a lot (a youtuber i loved for english was Mr Bruff)
I hope this helped, but it is different for everyone so do what you believe is best for you