JMHO but how confident can the OP be that he knows what the oil level was after the last change? If the level was not checked properly, i.e., on the jiffy stand and at full operating temps, the OP may not have accurate measurement data.
As has been previously posted, check oil at operating temps. at this point, the OP should not add any oil until he has drained whatever he is going to drain; ridden the bike to operating temps, say 10-20 miles and check to establish an accurate level. If low add whatever necessary to bring level up to or close to full. Ride again for just a few minutes and check. Now the OP has an accurate level, take a picture and ride for 1000 miles before checking again.
1/4 to 1/2 quart every 4K miles is nothing to be alarmed about. Also fill to full, don't buy into the "run 1/2 quart low" BS. If blow by is presenting, it's not the oil level but most likely the head breathers are not functioning like new.