Does the content look correct? Is your only objection that the file size is different?
On screen it looks fine but yeah the file size is worrying and the print jobs quite expensive...
I have a placed photoshop file in there (300ish MB) as a double page spread image just to name one so cant understand how it could be 36MB all in when exported in single page pdf (all presets).
Should I be worried?
What PDF settings are you using to export?
Are the graphics placed into InDesign layered files? If so, the PDF could be smaller because they get flatten (which can save a lot of file size).
Open it in Acrobat Pro, go to Print Production, go the Preflight functionality, and make all important test, like resolution, color space, etc, If this is ok and if you have exported with high quality it will be ok.
I would be more concerned to the huge INDD file, you mentioned. It sounds to me as if you are embedding imported images. Don't do that, link them, as embedding is the main reason of currupted files.
Take also care that you don't use EPS and use RGB images in InDesign.