Does breastfeeding affect regularity? I have a 15 month old and I got my periods make about 7 months ago. I have been fairly regular, within a few days. Now I'm a week late and took a test and it said negative. I am disappointed because I was ready for another. I still breastfeed at night so if that helps. I am really sad and could use some advice. I also had stabbing pain on and off in my woman parts when I was 2 days late, just that day though. And a burning throght yesterday. I took the test this morning.