Ladies help!

Prater
According to my last period I should be 6 weeks and 3 days pregnant. I went to my ultra sound today and I measured 5 weeks and 3 days and they didn't see a fetal pole or a heart beat. They said it was way to early. They also said I had some fluid in my Fallopian tube or my left ovary I didn't really know what he was talking about.  Has anyone else experienced this? Kinda freaking out because I had a miscarriage in October that lead to me getting a D&c. I just want a healthy baby!