What Causes Mild Spotting When Diagnosed With A Retroverted Uterus?

I have had mild spotting only following wiping after using the toilet. By my lmp I should be 7 wks 3 days but after mentioning the spotting to my GP I was referred to the hospital who did an internal ultrasound as they said I had a retroverted uterus. Sac measured 9mm but no yolk or fetal bone, said I looked more like 5 wks pregnant, last intercourse was 5 wks ago so is this possible (would they be referring to gestational age or fetal age?) Hcg was 7000 yesterday and I ve been asked back tomorrow for another test to compare.