I just wanted to echo ann's post, you are doing the best thing to have it checked out again for your own peace of mind and so that you can move on from here.
Let us know how you get on and remember we are all here to help and support you whenever you need.
Sorry to see you have this anxiety, which is fairly inevitable when going through all of this. If the dr can clearly see what it is on US, then they would not necessarily do a biopsy, so it is most likely correct what happened at your previous appointment.
You're absolutely right about the stats, bc is the least likely reason for your symptoms, but obviously you do need a clear answer on what it is, otherwise it will only play on your mind.
In view of your feelings now, you will obviously, ensure you get an answer you are happy with at the next appointment & be clear about the biopsy situation.
Hope this all gets resolved swiftly for you.