No gestational sac at 4 weeks 5 days

Tiffany

It starts from the bottom up. 1st was done at night on the 28th, second on the night of 29th,3rd 4th and 5th all done on the 30th at around 5pm. I'm 3 days late, went to confirm today at the doc, I am indeed pregnant maybe about 4 weeks 5 days, if not sooner.. he didn't an transvaginal ultra sound and couldn't see a gestational sac.. should I be worried? first pregnancy. I don't have a picture of todays test at the doc.. some advice please :)