My period came on 3 days this month when it usually last for 7 days. can i be pregnant

You may: As long as you are sexually active and not using contraception you can get pregnant. So if you skip your next cycle or spot do a home pregnancy test. Go from there.

Definate Possibility: Although menstrual period length can vary month to month, there is always a possibility of pregnancy when a period is shorter than normal. A quick pregnancy test will give you an answer.