The bucket is only 2.5 gallons and from the photo, it looks like it's only about half full of soil or maybe a little more. This isn't much soil. I don't know how long FFOF is suppose to be good for on it's own, but I don't think such a small amount of soil will last long. Don't fertilize it too much. I'd transplant to a five gallon bucket and make it full of FF soil. I prefer FF powder ferts over liquid as the powders you just put in the soil at a ratio of about 1/2 cup of fert for every two gallons of soil and just water when you have to. Takes all the guess work out and there's no need for a meter. Since it's been a few days since you've ferted, what is the outcome?