Sometimes my periods last for a day, at other times for three to four days. Is this a problem? Someone told me that this could be serious and it could be that I am not very fertile? Please help.
There is nothing wrong with that. its called an irregular period and its very normal.
At first, your periods may be irregular. They may not come every month (roughly 28 days), but more often (every 3 weeks) or less often (every 6 weeks). Don’t worry - this is normal. It can take up to three years for a woman’s period to become regular.
Remember that every woman’s menstrual cycle is different. To figure out how your own cycle works, jot down the first and last days of your period on a calendar for a few months.
A normal menstrual cycle lasts 28 days, plus or minus seven days. Menstrual bleeding is considered irregular if it occurs more frequently than every 21 days or lasts longer than 8 days. Missed, early, or late periods are also considered signs of an irregular cycle.
To determine whether your menstruation schedule is irregular, count from the last day of your previous period and stop counting on the first day of your next. Repeat this for three months. “If the number of days between stopping and starting your period is significantly different each month, you have an irregular cycle.
In many cases, irregular periods are related to a condition called anovulation. “This means that ovulation hasn’t taken place during your menstrual cycle, usually due to severe hormonal imbalances,” says Autry.
Sometimes an irregular period may be due to subtler hormone imbalances. You may still be ovulating, but the timing of your ovulation can vary greatly month to month. This is because lifestyle and medical conditions can influence your menstrual cycle.
Read some more here https://lovematters.co.ke/resource/menstruation .