Hello and welcome to HCM,
Passage of clot during urination does not indicate 
pregnancy.
First of it is important to ascertain source of clot, whether the clot was passed from the 
urinary tract or the vagina.
You have mentioned whether your periods are overdue or not.
If your periods are overdue, you may take an urine pregnancy test to confirm or rule out pregnancy.
However, the passage of clots need to investigated.
Passage of clots from vagina can occur in case of 
missed abortion.
However, a documented positive pregnancy test along is required to think for this possibility.
In addition, the clots passed need to be examined microscopically to look for evidence of products of gestation. 
Thus, I suggest you to post the detailed history - last menstrual period, day of 
unprotected intercourse, duration of passage of clots etc. You may consult your gynecologist for clinical assessment to ascertain the cause of bleeding or passage of clots.\
Thanks and take care
Dr Shailja Puri