What's a normal HcG level

Tiarne • 21 married and TTC #1
Just missed my period 3 days ago have had 3 positives starting out faint getting darker a positive at the ER tonight and a positive blood test my level is 37 they said I'm early maybe 3 Weeks but I need to have another blood done in 48 hours to make sure their increasing is this normal ?! I'm freaking out I found this online !