I don't think you should worry about pregnancy
from this incident unless she starts to experience early pregnancy signs
like weird cramps, fatigue, changes in appetite, smells, breasts, nips, peeing, backache, veins, acne etc. Trying to explain her discharge is not easy considering her irregular periods. Fertile mucus is stretchy between thumb and forefinger.
Sperm do not normally survive inside for more than 5 days, which limits how long before ovulation the intercourse is risky.