I understand what you are saying completely. I have acquaintances who had a 'binge night' of drinking and drugs and I can't imagine what (I stress the word 'acquaintances' as I really don't have much to do with them), when shortly after they discovered that she was pregnant. Even after all that, their baby seems normal and well. Now that she's 5 years old, I would think if there were some development issue it would begin to show, but she is completely fine.
So, seeing that, and knowing that folks like you and I are doing our best to reduce what we take, be well informed, well educated, and do the best we possibly can for our babies I think we're in the best place we can be.
I'm not saying it doesn't come with worry - it totally does. But, like my husband said yesterday, in looking at the risks, and knowing I am taking the lowest dose possible we likely aren't increasing the risks much more than what they are by being over 35 and trying to conceive. (I'm 38)
So, in the end, I just say 'okay, it's up to God. I'm doing all that I can, I've educated myself, I've asked the questions and I'm being as responsible as possible, it's up to him.'
I hope it goes wonderfully for you - please report in!
Ronda