Menses not here!

I am 5 days late. After giving birth, I had no issue with having my menses on a monthly basis. It always comes on time. Even before pregnancy, never experienced lateness - as far as I remembered. My LO is 7m - still breastfeeding. I can’t be pregnant right? Did a pregnancy test - negative. Is it normal to experience late menses after months of giving birth? I’m worried I might be preggo again 😵‍💫