Hello Luv2resq12, It is due to your lifestyle and stress and partially because of the side effects of metformin. You are unable to bear with anxiety as your period time approaches. There is fear of getting pregnant somewhere within you. Do not worry so much. Even if you get pregnant there are many doctors who can help you out of your problem. There is no need to take so much stress. You are getting symptoms of extreme fatigue, you should work on your diet and visit a doctor and get all routine blood tests done to rule out any disease that may be causing you discomfort. Anaemia is one of the main cause that makes people feel week and irritable. Just check it out. Eat food rich in iron like green leafy veggies, bananas, apples, berries, etc. Take juice, fruits and cereals along with eggs and meat to add more minerals along with antioxidants in your diet. Do not get obese, exercise daily. Do things that make you happy and adds to your health. Healthy lifestyle makes a person more beautiful externally as well as internally. Take care.