When it comes to the empty bladder thing I honestly think it just depends on the practice. 7 years ago with my first ectopic they wanted a full bladder. My second ectilopic and this pregnancy they've wanted an empty bladder each time, regardless if it was an internal or normal scan.
If you're only five weeks my goodness don't do anything drastic. Drs like to go by LMP and not ovularion, which I find ridiculous.
As far as ectopics go, I've had two. My first I blead from the start and didn't stop until I had surgery to remove it fromy tube. My second I blead at 6 weeks for 5 days and drs thought I was miscarrying. Regardless of multiple scans with each one, neither we're caught right away. My first was caught at 9 weeks and my second at 8 weeks. And my second they were specifically looking for an ectopic. I felt no pain or inkling something could be wrong except for the bleeding.