anyone??

Mi
Hey guys I need advice, I had protected sex Jan 11, had my period later that month and then February came, nothing, I'm in march and still nothing, the app says I'm 17 days late
My period is normally irregular and there is nooo possible chance of pregnancy, not sure why I missed my period but I need advice.
When I had sex there was no cum or precum near me at all.
Someone please help.
Also my cousin moved out of my house and our periods were synced and she left, my friend that I haven't seen in 1 year she moved in and she gets her period every other month, then she got her period this month but I still haven't gotten anything
Can anyone please answer to why this is happening to me?