As you said normally no auspicious event will take place in Aadi month in South India. The reason behind this is it is a rainy season and people undertake rituals for their late forefathers during this month. It is the last month as per Malayalam calendar. In Malayalam Aadi month is known as Karkkidakam. We do not use drumstick leaves during this month to cook food as in this month drumstick leaves will be poisonous. As far as I know no marriages will take place in this month. I have also heard that lot of people die during this month. Old people consider it as good if you die in this month as you can go directly to heaven. As the death rate is more during this month, people make "Karkidaka Congee" which is considered very good for your health. In short, it is a month of deaths and rain therefore no auspicious things will take place. The month followed by Aadi is Chingam, which is a very good month for South Indians.
"Do not give up, things might not favour you always"