Is burning sensation while passing urine a sign of infection?

Not because of the pus cells but because you are a female, at this young age you are prone to develop urinary tract infection. We need lot of information on your profile (such as marital status and history of sexual intercourse, child bearing) as well as the details of pain abdomen (its correlation to menstrual period) before we are able to give you an opinion. It would be better for you to consult a urologist and in turn he may like to have an opinion of a gynaecologist before he decides the line of treatment for you.