baby help please

Be
My last period was January 22 2017 and I was on progesterone to bring it down that month , here I am pregnate this month according to glow I'm 5 weeks 4 days , ok here's the thing that is scaring me , I went to the er sat because i had a miscarriage year and half ago so I just wanted to know what was going on , we did a transvag ultra sound and i sware we seen a 2.2mm. sac and also says on my discharge papers the same thing . My hcg levels were 800 , they just told me it might be way to early in the pregnancy, the next day the doctor calls and tells me he went over my ultrasounds and didn't see nothing that I have to come back in a week to redo ultra sound and hcg levels . I am so scared and think about it every second please someone help me