Just passed the interview!
I was first called by a Bulgarian officer who pulled out our I-129F and collected all the necessary docs that I brought with me. He asked me several questions about whether I've been in the US before, how I met my SO, and what he does for work. Then I had to wait for the interviewer to free up and start with the actual interview. The interview took somewhere between 5-10mins, she asked me the same stuff as the guy before her as well as questions about my time in the UK, the proposal and why on earth him out of all men around the globe.
Good luck to everyone!