Segue,
Maybe you have hidden the three slides accidently. See in the outline pane
on your left if the last three slides have a slash running through the
number. If so, right click on the slides and choose Hide slide.
Also check in Slide show - Setup Show - in the show slides section if the
radio button all slides is active and there is no range of slides that has
been set.
Also if you have applied an automatic slide transition of 0:00 seconds to
those last three slides they could flash by very quickly leaving you with
the impression that they have not been shown.