I am 23 , weight 46 kg usually regular on periods, delayed by 14days, with very less bleeding more lik clots. wt could it be?

A missing piece: of information is how tall you are. But you would have to be quite short, < 152 cm, to make 46 kg/101 pounds a normal weight. My suspicion is your low body weight might be influencing your periods. Irregular bleeding caused by hormonal fluctuations is very common. Of course, a late period can also be caused by pregnancy. Maintain a healthy weight; see doctor if menstrual irregularities persist.