It could be either pregnancy or you want the baby so bad your physically causing symptoms. Why will your doctor not do a blood pregnancy test or see you unless you get a positive urine test? Some women are unable to get a positive pregnancy test because their body does not produce enough HCG hormone. Did you take the pregnancy test in the morning with your first urine of the day? If not retest using the first urine of the day. Some health departments will see you to do a blood pregnancy test if your doctor will not do it. Good Luck and I wish you Baby Dust :-)
If you dont start your period a few days after it is supposed to come retest using a pregnancy test. You need to call back and make an appointment and not listen to the receptionist. They don't have medical training and can get in trouble for turning you away. Tell them you want a blood test and whatever it says is going to be more accurate than the urine test because it can detect trace amounts of hcg hormones if you are pregnant. IF they turn you away again I suggest getting a better doctor with a better staff who cares about you and your needs. Remember PCOS can cause you to miss periods and give you pregnancy like symptoms also.