My dear friend,
Let me explain you that 4 days delay (or earlier) is not labelled as irregularity in menses. Moreover, usually 4-5 days menses after is not a fertile window of a woman.
Woman releases her eggs, only once in a month and that is 14 days prior to the next expected menses. Considering 24 hours' life of the egg and 72 hours' activity of sperms, a week's period around the day of ovulation is fertile period. Your sexual intercourse was far away from it. So the chances of
pregnancy are very remote.
irrespective of your deposition or non-deposition of semen in the vagina, since she has got her menses, the possibility of her pregnancy is ruled out. However, I feel, I should make you aware of some fact.
Withdrawal technique is one of the very unreliable techniques of birth control. Even though the penis is withdrawn from the vagina before ejaculation, some secretion called as preejaculatory secretion (also known as precum in lay language) gets ejected in the vagina unknowingly. This precum does contain some sperms which are capable of causing a pregnancy.
Therefore my advice to you is to follow some reliable birth control method like condom,
intrauterine device or birth control pills. Now condom for females also is available.
I hope you take the advice for your future stress-free sexual life