In a previous post, you said:

" I need some pointers on what gear to get for snow camping. I have a zero degree bag, but I haven't really been happy with its warmth. The thing was $40 bucks and it packs down to nothing so that's why I've been using it."

I assume this is the bag you're talking about.

I'm afraid the fact is that if it cost $40 and "packs down to nothing," it's not what should be called a "zero degree bag." Even zero degrees Celsius (32F) is probably pushing it. Any bag suitable for use at zero degrees Fahrenheit will have an overall loft of 7" or so, whether synthetic or down.

This bag seems like it might fit the bill. 6.5" of loft, 3lb 5oz (not excessive for a winter bag) and a good deal at $139.

https://www.campmor.com/webapp/wcs/store...mberId=12500226

Consider carrying it inside your pack, at the bottom.