Skipped a period, Negative PT - EBF mom

Hello mga mommies, just want to ask if may nakaexperience ba dito na nagskip ang period nila pero negative naman ang PT? Exclusively Breastfeeding ako and 6 months na si LO. Weird lang kasi nung July up to September regular na akong nagkakaroon then nagstop netong October. No changes naman sa kain ko at matakaw pa din dumede si baby. Hopefully may same case. If someone can enlighten me it will be much appreciated.