Lots of mistakes and need help

Siobhan • 20 engaged and miscarriage mommy
I had unprotected sex twice.
Forgot my bc pill one day.
I was on antibiotics which may make it no longer work.
Then the condom broke when I was having a threesome but not while inside me. (Another condom was put on after) 
What should I do?
Get plan b??? I'm nervous and have a phobia of being pregnant please help