Well, I'm crossing all my fingers and toes for you! You're right, it is normal to worry but it doesn't matter if you do worry cause it won't affect the outcome. Equally though, getting excited won't affect the putcome either so you might as well indulge in both emotions, then if it does work out you won't have spend the first part of the pregnancy only worrying and you'll look back on it with fond memories iykwim.
I'm babbling on now, i'll shut up