Can i become pregnant 1 day after period ended and having unprotected sex? he didn't cum inside me but i am still worried...

Low chance: Sperm can live for 48-72 hours in the female genital tract and can fertilize an egg if ovulation happens. There are even some reports of sperm living as long as 5 days. If intercourse happened close to ovulation, than yes, there is a chance. If you are trying to avoid pregnancy, you should consider condoms or other forms of contraception.