HI.
I hope it is just some sort of strecthing or simliar going on for you, but I think if you are concerned you should go see a GP and get some more bloods or scan done before your next m/w appointment.
Ectopic pregnancies can go undetected up till 3 mths, with the body putting out the normal pregnancy signs during that time. If it ruptures (which its more likely to do more damage at a later stage) then not only is that a bigger risk for your future fertility but also your life.

Im not sure with your blood test, if it was normal range only having one test done cannot really say either way. They have to (as Im sure youve read) test every few days over a week or so to check if levels are rising properly. And after a certain stage of early pregnancy that becomes unreliable and a scan will be used to see if there is a viable pregnancy.

Best to go see your GP, rather than keep worrying.

All the best