Irregular period

So I've realized that my period has been a couple of days to a week late every month for the past 6 months and I never really thought anything of it until now. They've always been regular until after I had my first child a year and a half ago. It's really making my hormones go all crazy and I feel like I'm so exhausted all the time!! I feel like I go through my PMS period but the period takes an extra week or two to arrive leaving me super tired all the time. Anyone go through the a similar thing????! Help!