Your LMP was ended on 22/12 and you did sex on 29/12 with taking E.Pill Tab Postinor 2
on that day.
is possible only,if unprotected sexual intercourse is done with ejaculation around ovulation time in regular period. Other days are low risk and varies with high failure rate.
In your case,chance of pregnancy is almost nil as POSTINOR 2 is very much effective in preventing unwanted pregnancy with failure rate less than 1%.
After taking E.pill,you got withdrawal bleeding similar to period due to effect of POSTINOR 2 and it is very common & normal thing. So don't be much worried.
Next period may be early/delayed due to hormonal
imbalance. If you missed period,then do a urine for B-hcg
after 1 wk to exclude/confirm pregnancy.
Practice safe sex
by using safe period/OCP/Condom/E.Pill etc to avoid unwanted pregnancy & unnecessary vaginal bleeding.