you must have the proper levels of both estrogen and progesterone to have a monthly cycle. Stress can cause changes in hormone levels and that would affect whether you skip, have a light period, or a heavy period.
People are on here to help one another so one doesn't have to be nasty to others while we realized they can be under a lot of stress.
You need to get to a appropriate doctor for a full blood workup. Someone said thyroid and yes that can also contribute. Once they get the hormone levels, they will give you the appropriate hormone to balance.
exessive exercise could also contribute -- star atheletes are known to have suspended periods during competitions.
You need your hormone levels checked.
CaringSister54