Having irregular periods
is common when there are external stresses on your body. This happens when we are not used to the new environment. There are also several other causes for irregular periods. The one that I think fits
you the most would be PCOD. PCOD is polycystic ovarian disease
. In this disease, you might get hirsutism
and weight gain as well.
Regardless of the cause you need to consult a gynecologist. Hope this helps.