1gb for a big file like this with the layers is not that bad although it is still big, but so is the file dimension.
You will send to the printer a flatten file, not a file with layers. I doubt your file will be that big once flatten (eg. all layers merged into 1 layer); depending on the file format you'll choose as print-ready, it should be between +/- 50mb to 300mb.
If your issue is computer performance, then try using a publishing software like Indesign and use it to import your images and vectors separately. Add your texts in InDesign instead of Photoshop; create only the backgrounds and special effects in Photoshop. It's totally normal your PSD file is huge if you add many layers and all the texts as layers too.
If your computer can't take it, it's even possible you'll need to create different Photoshop files and add the merged layers into 1 file instead to not end up with too many layers!
I don't think you're missing anything, it's a big project! But maybe you could try Indesign and doing some elements in vectors if they can be done in vector.