? Beta abnormalities

Allison
Hi-
Found out I was pregnant last week.  Went to the MD and got a quantitative beta.  By LNMP dates I should have been about 5 weeks along, but was told my levels were more like 2.5 (unfortunately I don't have the actual number).  Took a pregnancy test at home today (one of the ones that estimates how far along you are and it said 2-3 weeks still.
This is the first time I've ever been pregnant, has this happened to anyone else, or should I assume it's non-viable?