The trouble with the stronger varieties of cannabis is that they can trigger bouts of psychosis, which if diagnosed as such, can be an outright bar to entry. Habitual recreational drugs use, without mental health issues can in itself be a knock-back at the medical, so it is important to be clear precisely what is on your medical records and to obtain copies for the medical examiner. The prescribed medication aspect will have some significance with regard medical suitability for service particularly in respect as to the type of prescribed treatment, the duration of the treatment and the recorded outcome. If you were prescribed anti-depressants for two months, for example, but only took a few days worth of them, then obviously if you can produce an unused quantity of the prescription, then it will add credibility to the claimed period symptom free. Good luck.