Im taking my pills properly and on time but i...

possible causes of your medical condition ?
OCP pills cause period irrgularties as a side effect , which is common in this case 
- its highly unlikely to be pregnant in this case because OCP is highly effective 
What to do next ?
 consult GYN doctor to do the needed routine medical test and determine the treatment pathways ( if needed ) , and the treatment options are :
- in case of hormonal changes , doctor may prescribe medication to correct hormones imbalance such as duphaston , which you should take a pill every 12 hours for 5 days  
- in case of thriod hormone abnormalties ( usually accompanied with other symtpoms ) , doctor will prescribe medication such as Levothyroxine
- in case of other chronic disease such as ovarian cyst ( PCOS ) or other disease , doctor may need addvanced examnation to determine the causes and treatment pathway 
- general advices : avoid stress  and have plenty of rest  and keep healthy life style including health diet and regular exercise 
Needed medical examnation :
physical examnation ,  Pregnancy test  ,vaginal culture and urine test, productive system ultra sound and  hormone levels including productive system hormones and thyroid hormones