I''ve been there.
Is it also possible that you have a fuel line
leak? If you can inspect the fuel line
and assure yourself that it''s ok then the leak must be in the tank.
I would siphon the fuel
down to what you think would be about half tank and observe if the leak persists. If it does, you must have a leak below the half-way mark.
If there is no leak and you add the fuel
back into the tank a quart at a time and watch for leaks you might discover a leak above the half tank line
. If no leaks show up, the problem must have been over fill.