Last month September 25-27 my period lasted for three days and again Oct. 22-25 it lasted for three days. But my normal periods last for 5 days. So now I'm confused, could someone tell me why my period is only lasted three days. Also I was bleeded heavy as normal and cramping but it's just short. Could I be pregnant? I'm only 20 years old. Could someone answer this question for me please! Thanks

It's possible, but it is more likely that your period is just off a bit. A few days different isn't uncommon. You could always try a pregnancy test, making sure you follow the directions carefully.

There are many chances to get pregnant if you do sex in periods or ending of periods without protection

I found some answers here it may help you

Sex within Monthly Periods

how to get pregnant

But try to take care always in periods.