Hi there your tongue was mine 10 years before my dx. I had a callous removed at the advice of my dentist. Biopsy came back as a callous..thickened skin built up to protect me from a sharp molar. 8 years later what may have started as lichen planus turned into a tumor in the exact spot the callous was removed. It wasn't an open sore - ever - just inflamed reddish and painful - but there was a lump there I thought might be scar tissue from the removal of the callous. The first ENT I had didn't notice it. Biopsy came back inflamed tissue. he said to have the tooth filed and be checked for allergies. Two years later I have a tumor 2.4 cm x 1.4...
I m so glad your biopsy was negative... Just keep a close eye on the area - any pain in the future and go to see a well qualified ENT.

best of luck. We're all individuals - my story may never become yours but forewarned is forearmed.

take care