Without a hydrometer, there's no way to tell if it's safe to bottle. It is possible that the yeast is not active and what you have is simply dissolved gas rather than active production: the CO2 produced from fermentation first must saturate the solution as dissolved gas, and then the rest evolves out the airlock. When fermentation ceases, you still have all that dissolved gas in solution. This is why degassing is typically used, gently agitating to force dissolved CO2 out of solution. Racking also promotes degassing, but with one-gallon batch sizes the losses incurred by racking can be an appreciable fraction of total volume.
For now, I'd make sure it's warm enough to naturally degas (room temp) and consider actively degassing it if it's not sitting on lees (sediment).
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