Why is it taking so long to stop when braking even though the fluid levels and supposedly the brake pads are fine?

Could be the master cylinder, booster, or the brake cylinders. If the pistons in the wheel cylinders are jammed up, you don't have any braking on that wheel at all. Does the pedal stay steady when you hold the brake down? If not, it could be a leaking master cylinder. With power brakes, if the booster isn't working it takes a lot more pedal force to apply brakes than you expect, which would also lead to long braking distances. Another thing to look for is the brake pads/shoes or rotors/drums have not glazed over. The effectiveness of the braking action will be greatly diminished with either surface being glazed - rough up the pad surface, or have the rotors lightly turned. On a similar thought, if the pads / shoes have become contaminated with grease, oils or similar, they'll need to be replaced.