AF skipped a month

In the last two years I have noticed that everyone once in a while AF will skip a month. I am 14 days past AF arrival and have 2 BFN with hpt. I get slightly nauseated when I eat but not all the time but often enough for me to recognize it. I am extremely tired all the time. But that's it... Maybe it's because my body is ready for daylight savings. I find myself looking for any sign but figured this far with missed period a test should show. Does anyone else have random months of a missed period. I should note that my periods are usually spot on and only last 4 days. My last months was only 4 day but pretty light compared to my norm. Advice or just thoughts would be helpful.