If someone had a full regular period after taking the two Plan B pills, that means she is not pregnant?

What if she took the two pills(says to take 2 doses in different time frames on box,was almost $50 too) very early before the 72 hours.Took it early right away because on the first day had short unprotected sex and the partner claimed that he pulled out. Next, noticed spotting but the box said it’s normal to spot when the pill was taken. Then after a few weeks, got a heavy menstrual period in just only 4 days even though the last normal period cyclewas like 6 weeks ago in October.

If that occured does that mean she isn’t pregnant at all and the Plan B was very effective or is it still necessary to wait to see what happens to notice any pregnancy symptons and take a home pregnancy test?