Thanks for the query.
The possible causes for your bleeding are :
imbalance, leading to delayed periods. This can occur due to causes like ploycystic ovary disease, lifestyle modifications leading to weight changes etc.
hormonal abnormalities can also affect the menstrual cycle.
-Sometimes urine pregnancy
test kit may not give accurate result especially in early pregnancy. So the possibility of pregnancy also cannot be excluded completely.
So you once consult gynecologist, get examined and go for ultrasound
By this the possibility of pregnancy can be ruled out and also the cause for your problem can be identified and treated.