Hi DV! Such a cute DD!
As you probably know I moved from a 4 bedroom house to a 1 bedroom apartment less than a year ago. (From 2000 to 700 square feet if that helps, also from the house where my children grew up.)
One thing that helped me was visualizing what I wanted my new apartment to look and feel like. This made many decisions easy.
Which leads me to my next idea--get rid of the easy stuff first. The things that obviously won't fit, or that you clearly don't need, or that are not useful or beautiful.
Next, give yourself a little bit of a break on stuff that's super hard. Either super hard to get rid of, or worse, hard to make a decision about. You can store a few boxes for a while, either in your new home, or....
Be okay with renting a small storage unit. I was completely against storage units and had never had one, but in order to make the transition, I got a little one. In it I stored my refrigerator, my washer and dryer, two treasured stuffed armchairs, the rocking chair where I rocked DDs, and a dozen or more boxes. At this point nine months later, I have given the fridge and an armchair to local DD, have made room in my apartment for the other armchair, have made peace with giving away my Maytag washer and dryer, and am girding my loins for unpacking several boxes of books into my new iron shelves, and figuring out what to do with the rest, since I don't want to pay the monthly fee forever.
Remember that you can keep culling after you move and that you don't have to do the perfect cull on the first try.
Meanwhile I have a (to my eye) lovely apartment, completely clutter free, and full of items that are beautiful and of sentimental value to me. It is my favorite place I have ever lived.
I found the downsizing difficult and overwhelming and downright scary. However the dream of a pretty and peaceful apartment sustained me. And the belief that I didn't have to do all of it 100% at move time made it possible.
I know you will do wonderfully! Can't wait to hear more!