am i pregnant

so me and my boyfriend did the dirty with no protection and he came in me on august 23rd so the 24th around 10am i took a plan b then i started bleeding the 31st of august to the 5th of september so i took a pregnancy test early on the 9th came up negative so i waited and i was supposed to get my period the 16th so i too a test on the 20th came up negative 4 days late now it’s the 23rd 8day late i been getting tiny cramps here and there bloating a little no still no period! can someone explain this to me and this was my first time using a plan b