Going to the Reformed Government is lengthy process.
You need to build Migration, Warrior Horse Herds (something like second tier nomad barracks), a Market and Settled Community. Only then you can proceed towards Reformed Pastoralism and Settled Aristocracy and 10 turns later you can have Reformed Government that allows you to build most advanced buildings and normal barracks.
If you mess up the order of building and build Reformed Pastoralism too soon before you have all the buildings ready for later... you won't even see the reformed government buildings in your queue. Maybe that's what you're doing wrong?
To top that you can't have reformed govt everywhere
Here's the map of Reformed Governments: