very less bleeding as compared to her normal period

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If she has taken emergency contraceptive pills within 24-48 hours of the unprotected sexual intercourse, it should work in preventing pregnancy (provided you were not sexually active without protection after taking it). Withdrawal bleeding usually occurs within 5-7 days of taking the emergency contraceptive indicating that the pill has worked (which may not occur if the pill has been taken very close to your last period). Since the emergency contraceptives contain high doses of hormones, these can disrupt the normal hormonal and period pattern. Wait and watch for her next periods which can be delayed (count the usual menstrual cycle length starting with first day of her withdrawal bleed). If pregnancy is suspected, she should consider visiting her doctor/gynecologist at the earliest for thorough examination (to confirm pregnancy related changes/signs in body) and blood/serum HCG level test (to confirm/rule out pregnancy accurately).
If pregnancy gets ruled out, and if you intend to remain sexually active, she should consider visiting her gynecologist to get started on suitable regular birth control measures to be protected (after her periods). She should be regular with birth control use as instructed. Avoid having unprotected sexual contact.
Take care.