Somehow my pregnancy doesn't seem real...

I don't understand it. I tested positive at 5 weeks on urine and blood tests. I just finished 8 weeks and have had very mild symptoms ranging from occasional nausea to fatigue. Obviously my period has not returned. Still I find myself checking out home pregnancy tests at the store, wanting to test if I am really pregnant. It somehow hasn't sunk in yet. This will be my second child. I have my dating ultrasound on the coming Friday. Maybe that is what I need... to just see the little one. Anyone else feel the same?