Display a list of child pages on a parent page in WordPress

Hello,

I want to display a list of child pages under each ‘Blog’ category on my website http://www.stephenmcquinn.com.

I intened the path to be:
Hover to ‘Blog’ on the nav bar
Choose a category e.g. ‘Web Development’
Which would lead users to a list of the web development articles (the child pages).

I followed this tutorial http://www.wpbeginner.com/wp-tutorials/how-to-display-a-list-of-child-pages-for-a-parent-page-in-wordpress/ and managed to add a list of child pages on the ‘Web Development’ category as you can see here but I only intended to show the child pages of the ‘Web Development’ page but as you can see, the list shows all the child pages that are on the website.

Instead, I only want to show a list of the child pages for each particular parent page.

Hopefully this makes sense, let me know if I need to explain myself more,

All the best,
Steve 😀