DVDdoug told you about two resistors (resistor for transistor base and resistor for led current limiting). Do you see those resistors in your schematics?
BTW, if you power an 3W LED, even a blue or white one with 3.2V forward current, from 5V, something (either the current limiting resistor or the transistor in an opamp based CC supply) will have to dissipate almost 2W. Keep that in mind.
An alternative would be a switching CC supply. In my experience, those are better bought. Meanwell has the LDD series, but for a single 3W led they are overpowered. I am sure someone can point you to an IC.