Changes in months changes in period???

My Glow community I need a bit of advice....I was wondering if anyone has ever been late but right when the new month started u got ur period??? I haven't really been late really. This month I haven't gotten my period yet I did have a bit of spotting about a week ago & right when I thought my wonderful friend was coming it didn't. Now tht December is almost here I am having a bit of cramps not bad ones. Like I said this isn't the first time this has happened to. Last yr it happened in February & November just with November it went into the beginning weeks of December. Me & my boyfriend really haven't had a lot of sex {{Shocker lol}} this month. Has anybody else ever gone through this or is?? Just wanting sum input before I got calling my doctor...Thanks everyone