HCG level results

Okay so I got my HCG level results today they were 2,386 my last results from 03/11 were 1026 so in past 10 days only double once which based on what I find on the internet is not a good sign especially given the Ultrasound showed nothing yet.  Spoke with the nurse today they want me to come back Monday for another Ultrasound asked them if I could just wait a few weeks they said no because their afraid of ectopic or something since my HCG levels over 2,000 they think they should be able to find something.  Although the nurse said in the ultrasound they did yesterday the technician scanned my fallopian tubes and did not see any sign of ectopic pregnancy.
My thought is it could be three different things maybe my bleeding in February 28th was actually a miscarriage but my hormones just have not adjusted yet.....or I will have a miscarriage or I actually by some miracle conceived in March not in February and my hormones jumped up very quickly and it is just too early to see anything thru the ultrasound.  Trying to stay positive I mean at this point I just want to know one way or the other.  If I am not pregnant I will move on but its hard right now not knowing or having any control.