chelle792 Welcome to the Kult! Congratulations to you and OH on your pregnancy. Exciting times! 
Look at the previous Kondo threads1-7 - they have the categories listed.
It is easier to deal with one type of item at a time, otherwise, as you have found, you end up with a messy pile of assorted Stuff without a home!
So, the first category is clothes, which, to most people, is the easiest... unless they're at some point in reproduction!
They have a home.
Pack away all the clothes that don't fit now. But, chuck any that didn't make you feel joyful to wear. Checkout YouTube and learn to fold and file your underwear and other clothes - this releases space, and makes each item instantly identifiable and easy to retrieve.
The next category is books, which usually have a home, too. Handle them, but don't open them. Decide whether they bring you enough joy to outweigh the space they take up.
Avoid bringing anything into your home that is not essential. Look on some of the threads here when you are considering baby clothes and equipment - much of it is not essential.
Buy the book! And read it. This is the map to a calm, life.
Follow the categories, although you can do them out of turn if really necessary. If you do follow them faithfully, it builds your decision-making ability and strengthens your motivation.
Do NOT try to sort by room! You need to have a firm focus on the task in hand. Trying to do a room, or miscellaneous cupboard is full of distractions.
Good luck.