Stopped BC and no period!

I had been taking birth control for two almost three years. I stopped taking my birth control durning the first week of a new pack because I had gotten a UTI and the nurse told me the medication was going to cancel it out my birth control anyways. My last period on birth control was 6/8/18-6/11/18. I was waiting to start my birth control again until I had my next period. It’s now 11/25/18 so I’m 20 weeks late. I’ve taken about 12 pregnancy test over this time and all of them come back negative. I’ve gone to the doctor and the blood test and all the other things they tested for came back negative. She basically told me that there’s nothing they can do for me and all I have to do is wait. I just wondering if anyone has experienced anything like this and what the outcome was? My fiancé and I are not necessarily trying but we are not going to be upset if it does happen.