Low HcG

I took a urine test today & got a faint line! So I headed straight to the Dr. to confirm with blood... Sure enough I am pregnant! I am so excited. However, as I was leaving the dr. said I need to pull you back in here. She wants me to come back in 2 days to see that my HcG level is going up. Today mine was 15.45, I am anywhere from 7dpo to 13dpo. Does anyone have any good vibes or advice? I've read 15 is fine as long as it is going up! I just need peace of mind while I wait!