I can confirm that you are subscribed to the Specialist plan. You can check this by navigating to your organisation portal and selecting the “Manage Users” tab. There should at least be a Specialist seat that is available in your organisation.
When you look under “My Plan”, that shows your own personal plan which is only relevant to the Open Use and Consultancy plan. Purchasing either an Enterprise or a Specialist plan will make “Enterprise Memberships” appear and create your organisation portal. If you are able to see “Specialist seats” under “Enterprise Memberships” then that means that you are subscribed to the Specialist plan.