Yes, pwedeng-pwede po. LAM in breastfeeding is only 98% accurate and only in the first 6 months post-partum.
Ang menstruation po kasi is our body's way of disposing the unfertilized egg. So kung nag-ovulate na ulit at nafertilize yung egg natin then diretso pagbubuntis na yun and there'll be no need for menstruation.