B was born in the summer, by the time it was cold he was mobile so he needed a jacket.
I'd think with a newborn though that you'd be fine with blankets and swaddling - I know they make little blanket looking cover things for carseats too, that would probably work really well.
My son was born in Oct and we had all of the things you mentioned above, plus the light weight JJ Cole Bundle Me. We only got this because it was on sale at a ridiculous price when BRU moved locations. We ended up not using much since we hardly went out anyways.
I think you're good.