Feeling Anxious

My anxiety grows as we get closer to our first ultrasound on Monday, all I can think about is what if they don't see a baby? That's what happened last time, there was a yolk sac and nothing inside, I fear the same fate for this baby.
Maybe it's because I don't have the experience of a positive outcome to go on, or maybe I'm just freaking myself out for nothing.
This whole experience has me to the very edge of my sanity with worry, happiness, excitement and fear. I've never been on such an emotional roller coaster.
Those "what ifs" that usually plague me around the time of IUI are back again. Mike is so wonderfully positive about the whole experience, and it's so hard for me to feel that with him, I really really want to, but I also need to protect myself from the disappointment that could happen again.
I wish I had a Crystal ball that could tell me things will be fine, or they won't, but either way I would be prepared.
I hate being unprepared, I like information, I need to know where I stand at all times - this has me completely swimming in uncertainty.