Sounds a bit early
At 2-3 days after having sex
, a woman can feel pregnant but that's so early that it is probably her own mind playing tricks on her. At 1 week after having sex, if the woman is super-sensitive to little changes in her body, she might truly feel pregnant.
In reality, none of this is important because the days pass so quickly, and she will know in another few days when she misses her period.