I've been feeling that way too, kind of. Except all we have is a few diapers and some clothes. We aren't getting a crib or bassinet or anything at this point, or very many "big" items, so I don't feel too worried that way, but I'm extremely overwhelmed with having to find a car seat that will fit in our car with DD and DS' car seats. We'll have 3 car seats in our Sable, which I've heard is one of the better ones for that, but still, I'm so nervous we won't find one we like/feel comfortable with *and* that will fit. That's what's overwhelming me right now.
I have to suggest the DIONO/Sunshine Kids RADIAN car seats.. they are a bit more pricey.. but they are SUPER safe.. have excellent ratings and they are made to fit 3 across a sedan.. I have had 2 of my nanny kids who were 7 in them.. still harnessed! I prefer them 100 percent over Britax.. they may cost you a bit to invest but way cheaper than a new car.. and you can put a newborn in them :) they sell them on Amazon