5th pregnancy but no babies yet

Hey y'all! I'm 5 weeks today with my 5th pregnancy. I've had 4 miscarriages so I'm nervous but excited! My symptoms come and go which freaks me out when they go but blood work has been good so far. I thought I was further along and went in for a US but they saw nothing. That scared me so bad but the blood work put me at about 4 weeks at that time. I guess that's super normal to not see anything that early, not even the sac!