Hello dear,i understand your concern.In my opinion there are various causes of irregular periods like stress,overweight,obesity,polycystic ovarian disease,thyroid abnormalities etc.I suggest you to repeat the urine pregnancy test after a week.If it is negative then consult doctor as you might need evaluation for irregular period and irregular spotting.If you had any unprotected intercourse then it gives a suspicion of pregnancy.Usually a urine pregnancy test gives accurate results a week after missed period.But as you have irregular cycles the period cannot be expected.Ultrasound might confirm the diagnosis.Also serum b Hcg also might help in ruling out the pregnancy. Best regards....Dr.Srilatha