Katabelleh, I know exactly how you feel...
The only upside to this is that DD's nappies don't bother my weak stomach so much now that I can't smell anything anyway...
From what I have found out, some sites say, it is fine to do (and best after consulting with your GP about it), but to really keep it in moderation. The reason for this being that some women have chronic stuffed noses during pregnancy and if you get too used to using decongestant sprays, they can end up having the opposite effect. It also seems that there can be a vast variety of ingredients in those sprays and some just haven't been studied enough in regards to their effect on the developing baby. But I wish someone could give us more definite information...
I'm usually not one to use a lot of medication at all, but it would be nice to be able to use it, only for when it's really bad...

Saša