Let's start by getting the negative stuff out of the way. One reason to curl up with your own book is to find errors. I'm not suggesting you 'proofread it' again, but take note if you notice anything that you might've missed during the editing process. Do you see something you should've added or could've taken out?
Of course, we're all a work in progress so reading your book also allows you an opportunity to see things you can improve. What would you do differently in the future?
At the same time, don't forget everything you've done right! What stands out about your book? Did you write snappy dialogue? Was there one particular scene that stood out? What grabs your attention? Try to see it through the reader's eyes. Don't be your worst critic but remember to pat yourself on the back for what you've done well.
And finally, why not read your book? You've worked hard, so why not snuggle up with a hot drink and get lost in the fantasy that you created.