What do you think were the reasons behind getting those results? I'm not sure if your college will let you resit the Biology AS and Chem AS and do A2 at the same time, and even still, that is a hell of a lot of work. Obviously you won't be able to apply to medicine this year, unless your teachers decide to predict you AAA. Your best bet to study medicine is applying next year and sitting AS/A2 Bio and Chem next year along with A2 Psychology, if you can do that, to bring them all up to AAA.
Edit: even doing that will limit your choices because some medical schools have a limit on how many modules/exams you can resit (e.g. Edinburgh), and some want reasons for any resits. Your A levels must be done within 2 years completely, and AAA achieved, to apply for medicine unless you have extenuating circumstances.