I keep wondering the same thing, so i feel your pain. Because I was in fertility treatment already, they do early monitoring scans. We have one this Thursday at 6 weeks 2 days and they told me, "we'll probably see it". (no question at all as to how far along I am, as I was being monitored)
I know for both of us, it's totally normal if we don't see it. But I also KNOW (without NO doubt) that I'll worry if we don't see it, no matter how illogical it may be.
I guess that's parenthood.... ;-)
I'll let you know how it goes for me.