5.030 hcg blood test at 8 weeks!

Hello I'm currently 8 weeks and 4 days No symptoms

except for sore breast( but not very) only the nipples that hurts., I'm having pms and my lower back hurts. I also can't sleep good and wakes up early because of pain. not too painful but it's uncofortable

What happened before:
-I had pt and it's negative

when I was 6 weeks:
-I also had transrectal ultrasound/pelvic ultrasound during 6 weeks and the doctor can't see anything.

May 30
--I had spotting - a very light blood in my panties just two dots- I thought I was going to have my period again.But it didn't continue, although I'm having mentrual cramps.

-I had a blood pregnancy test the other day july 14, 2011


I'm 8 weeks pregnant and no symptoms.I had blood test with the range 0-5 and I got 5.030 and the doctor said it's positive. but very very low.

what's going on. Is my HCG low for 8 weeks? Or I'm having problem.. :( They can't tell coz they can't see anything trough ultrasound too.

they asked me to take pt and ultrasound after 2 weeks. but I want to get it now because I'm worried! help!