What Causes A Delayed Menstrual Cycle With Unusual Urine?

Hello i'm 23 yrs old and my menstrual cycle has been late the past two months by a few days… this month i was expecting my period on the 8th and still nothing… I took 3 pregnancy tests and they all came back negative… my urine is dark yellow and sometimes has mucus spots in it.. What can be wrong with me???