What do you mean your extruder diameter is 1.75? Are you saying you have extrusion width set to 1.75? Just because you have 1.75mm filament?
The diameter of your filament has nothing whatsoever to do with your extrusion width. Your extrusion width is more determined by your layer height. although it is limited by your nozzle opening size too.
As an example, I have a 0.5mm nozzle. My layer height is set to 0.2 and my extrusion width I have set to 280% - which works out to be 0.56mm. By the way, I use 3mm filament, but 3mm versus 1.75mm filament will only change your calibrated E steps/mm - you will need fewer steps to extrude the same volume with 3mm filament.