Hi there - sorry you feel like you've been going in circles, let me try to help. :-)
Your name servers are already correctly pointing to WordPress, as I can see on your whois domain record here:
Registration Service Provided By: Namecheap.com
Domain name: slightlyoddley.com
So that part doesn't need to change, as it's already set properly.
In order to complete your email setup, you'll need Namecheap to provide you with their custom DNS records for email service, which you'll then enter into the Custom DNS area of your domain setup, under Store > Domains > Edit DNS.
For an example of what the records will look like, you can see screenshots on the support page Jenia gave you above:
Please make sure Namecheap is clear about the fact that you only require their email service, not web hosting, since you are hosting your site at WordPress.com. You've already set up your name servers to point to WordPress.com, but in order to use Namecheap's email service, you need the appropriate DNS records from them, such as MX, A, and CNAME records, as applicable, and as seen in the example on the above support page.
Let me know how it goes.