Well, your wife certainly can't be conceived at this point (that happened a long long time ago
) but as for the risk of her conceiving if you have sex during her period, that is probably the time with lower risk, first day haivng the lowest risk.
As for the statement "a woman can get pregnant at any point during her cycle", that's not technically correct. A woman can only get pregnant around the time she is ovulating, and if she has a regular cycle, that is not
going to be around the time she menstruates.
As for withdrawing, yes that helps, but it's not guaranteed. Both these methods (withdrawal and rhythm) are very risky.