Need URGENT advice !

So my period was supposed to start Friday but it didn't... My cycles have been off but last month it can't right in time. so Saturday night I had protected sex with my boyfriend but he took of the condom and did once then stopped.. So paranoid I Took Take Action Levonorgestrel on Monday (48 hours after) just in case . Now I'm 4 days late.. during the time period from having sex and getting to take the pill on Monday my period still didn't come. now I know after taking the pill theres side effects and can cause a late period. My main concern is...

Would I get pregnant is there even a minimal chance?

I'm confused on why me period is Late ?

if this is my second time having sex last time it was in September.