Oleander grows vigorously and requires annual late-winter pruning to maintain a small size and attractive shape. Maintaining a 2-3-foot-tall oleander plant, though, is unrealistic, unless your oleander (Nerium oleander) is a dwarf cultivar, such as 'Petite Salmon' or 'Petite Pink', which top out at 3-4 feet tall. If you trim the plant back to 2-3 feet tall, it will send out new branches just below the cut, leaving the base of the plant bare.
That said, leggy stems indicate that your plant needs corrective pruning. Begin by completely removing one-third of the large, woody stems. Cut the remaining stems back by one-quarter of their height. Late next winter, remove several more of the large, woody stems if necessary, and trim back branches.