When I first found out I was pregnant I was soooo excited I couldn't wait for my little one to be here.  It wasn't until I was about 6 months that I started questioning things and feeling depressed and hard on myself.  My first question was, how accurate can these ultrasounds really be and how do they even come up with these measurements.? The second and biggest question is how do they know when you conceived if you don't have regular periods?   I thought that I conceived in October so here I go in January for an ultrasound and I'm only 8 weeks.  So that really threw me off.  This whole  pregnancy has thrown me for a loop because I didn't think I would ever get pregnant. But here I am! Anyone have any information on how accurate these ultrasounds really are and if it's possible for one to be off a few weeks?