Hey! Looks like I'm in the same boat as you
I too want to go into medicine and and am predicted 8 A*s this year. Right now, my school isn't very supportive in getting anything but a pass grade, we haven't even gotten half way through Biology, but I made sure that I self-taught during the summer holidays last year (Yes I am a 'no life' lol).
It’s definitely clear that there is not a huge amount of time left at all, but here are my methods of revision which help me to get it in done in depth and quickly:
1) Use the specification religiously: If you don’t know what it is, it is a document that your exam board will publish with all the information you must know for the 2014 exams. The rule is, if it’s not on your specification, don’t bother
2) Make notes using your textbook and specification together in a notebook
3) Now, that the content is done, do all the past papers you can access, every single one!
4) Mark all of the past papers and identify areas where you are struggling and go online, ask a smart friend or teacher to explain. Keep in mind that you should never worry about annoying your teacher by asking them to repeat things if you don’t understand, because in the end, it’s what the teacher is getting paid for.
I know that all of that information seems like a long process, but trust me, if you work in your lunch times as well as after school, you will get a year’s worth of curriculum covered in 3 days if youre fast and max. 5 if you’re a slow learner.
It seems like too much to fit into seventy days, but it's only a psychological thing: If you try to look at it from a different perspective i.e. make targets for the week, you will find that the time wasted from not being able to work efficiently because you are stressed, will decrease significantly.
I'm sure that it is more than possible to finish the subjects in depth with a lot of practice; It will just mean sacrificing a social life and everything else which is unnecessary
You can do it!
PS: What subjects are you taking? That might help a bit when giving advice! And sorry for that being sooooooooo long. Hehe.