You took regesterone
tablets for 3 days and stopped just 2 days back.
After taking the tablets for withdrawal bleeding, you should wait for upto 2 weeks for the periods to come.
The urine pregnancy
test is quiet reliable test for diagnosing early pregnancy.It generally should come positive after about a week of missed periods if pregnancy. But, if you are very much concerned, you can get blood B HCG
levels, which will diagnose or rule out pregnancy for sure.
Once pregnancy is ruled out, you can safely wait for the withdrawal bleeding for upto 2 weeks.
Hope to have cleared your doubts.