1st doctor appt

Went in this morning to see my doctor because over the weekend I got my BFP! Did a urine test, transvaginal ultrasound and blood work. Urine test showed a faint line line my hpt. Then during ultrasound she said she saw thickening of the uterus (like my body getting ready for a baby) but she could see a sac yet and I haven't got my blood work back it takes a week. Do you all think I am worrying for nothing or should I be worried? I mean the first day of my period was Nov 6 and I should be four weeks....?!? I thought by now you could see something... Worried sick..