My first biopsy was diagnosed as Lichen Planus. I too was given steroids, but all they did was make me drool.
It seemed like after that first biopsy, it 'triggered' something, and 3 months later it was obviously a tumor. My ENT knew it was cancer then, but a second biopsy only showed Hyperplasia. The same sample was retested and it was SCC.
As far as I know, Leukoplakia is an unidentified white patch that can't be scraped off. It can be many things, including Lichen Planus.
However, unlike you, I only had a white patch on the side of my tongue - not anywhere else.
Lichen Planus can mimic the symptoms of cancer. It can cause severe pain on your tongue that radiates to your ear and throat.
The fact that you had a CT scan and nothing showed up is great! But if you drink and/or smoke you should quit to lessen the risk of it developing into something else. If there is a tooth irritating the area - get it fixed.
Most Lichen Planus DOES NOT develop into cancer, but it can be a warning sign that you need to pay attention to, if it changes in any way.
I don't think there is a cure for it, but it's been a while since I've done any research on it - maybe there is one now?
The chances are, Lichen Planus is all you have. Just keep an eye on it and let us know how you are doing.