Relax. Don't think of cancer at this age,with those symptoms. It may be simple urinary infection. Get urine microscopy done.
Coming to irregular periods weight reduction helps a lot in correcting hormonal imbalance and helps to get regular periods.
Next Steps
Drink 3-4 liters of water daily.
Daily exercise
Weight reduction
Diet control
Health Tips
Have low carbohydrate diet, low fat, high protein diet
Do the above and give some time.