Seperating them was the right thing to do, even though it takes forever. I'm not sure it was a good idea to chop the tops off before they had a chance to establish. If I were you I'd plant the tops too.
Generally works best to seperate from bunch and plant them individually, about a cm or so apart. Probably sholuldn't have chopped the tops off, but you can try and see if you can plants those as well. The tallness generally comes from not having strong enough light (glosso is generally a "high" light plant). If you're lacking in light they will grow more vertically, if you have enough light they will spread out horizontally and stay close to the ground.
However, since you chopped off the tops its hard to say if the light strength is the issue without knowing more. What's your setup? Lighting, c02, ferts?