Can you get pregnant if you had sex just 3-4 days before your period is due ? because i heard its a low chance but i want to be positive?

Pregnancy has been documented from unprotected sex on any day of a woman's cycle, including during menses. This would be less likely if cycles are regular/predictable. Those with irregular cycles have unpredictable egg release dates. If you are lucky this time don't plan on it for the future.

Pregnancy is known to have occurred from sex on any and all days of the cycle. If you miss your period by 4-5 days, do a home pregnancy test. If the result is negative repeat the test in 4-5 days. Use first morning urine and follow instructions for the test carefully. If you do not wish to be pregnant, use contraception all the time, every time. You may consider implanted contraceptive, or IUD.