Unprotected sex on last day of period is very much safe and there is no chance of pregnancy
As you took contraceptive
pill yesterday, a withdrawal bleeding comes out within 7 days. Next period may be earlier or delayed due to hormonal
Pregnancy is possible only,if unprotected sexual intercourse is done with ejaculation around ovulation time in regular period. Ovulation occurs approx 14 days before due date.
, wear tight breast support, take healthy diet, maintain genital hygiene, need proper sleeping and practice safe sex in future.