no period yet

So my period either usually comes early or on time but it hasn't came yet this time (also my husband and I have been using the pullout method and has had no slip ups) but I've also been working out and heard that, that could affect it, but I'm not too sure because it's just something someone told me. Also I'm 5 months pp so could my period still be trying to go back to normal? And has this happened to anyone else?