does cause amenorrhoea (absence of periods) because there is a lot of hormonal
imbalance happening in your body. If you are under a lot of emotional stress and the fact that your are physically stressing out your body too (poor eating habits, increased consumption of alcohol) is definitely adding to your problem. If you have been taking birth control pills for quite some time, then chances of a pregnancy
are anyway slim.
What you need is stress management
and dietary changes to cope with your issue. Also homoeopathic treatment can cure your PCOS completely and avoid future complications like infertility
All the best!