Thoughts please

Hey, My partner and I are trying to conceive our second child, Our first is only 7 months old and I have only had one period since having her which was when we started weaning her. I am now two weeks late for my second period and hoped I was pregnant, but I've taken three test all of which have been negative, is this just my body settling back down through breastfeeding? Or do you think there is any chance I might me pregnant? Am I grasping at straws?