two weeks before her due date is her most fertile time. foreplay would have caused arousal for you and there would be leakage of pre-ejaculate. those 3 unprotected minutes could have released small drops of sperm before you put the condom on. my verdict is - she's most likely pregnant.
my gf's period is late over 10 days now. we did have unsafe sex after foreplay like 3 mins and wear condom. pregnant?