Pocket Pet Portal can be also bought from Madeline Netley in Stormsong Valley and Happy Holaua in Dazar'alor for 1000 polished pet charms. ATT shows only old source - reward from achievement Battle on the Broken Isles.

Edit: Interdimensional Pet Portal also should have Madeline Netley as a source. Now it has Happy Holaua only.

they're both there -- i'm not sure why they're not showing up for you. :\

If you toggle Debug mode on, does it show all sources for you? If so, your addon settings may be impacting how many sources are displayed for you. Check the "Locations" slider option and increase the number of sources to list if the value is set to 1.