Hi, Welcome to HealthcareMagic!
Dear, as you have informed, your LMP was 25 Dec
, so If we take a regular 30-day cycle, you might have ovulated around 9-10 Jan. The ovum (egg) will not remain viable for fertilization 48 hr after ovulation, so it's highly unlikely that you had a fertilizable ovum in you at the time of sexual intercourse. Therefore, chances of pregnancy
are remote. Still, you may take i-Pill to completely remove the chances but it's not necessary. It only may be that this time your cycle is slight irregular.