Hi Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concern...
No withdrawal bleeding is not a must posts intake of emergency
contraceptive like I-pill. Withdrawal bleeding could occur within 3 weeks of intake of the pill, so it may follow soon. Withdrawal bleeding is a sign that intake of I-pill was successful in preventing
pregnancy through disruption of menstrual cycle. However in some cases withdrawal bleeding may be absent & still the woman may not get pregnant
I would also like to tell you it is better to take I-pill as early as possible after sex. It has high success of 95% when taken within 24 hours & success decreases to 70% when taken 48-72 hours as you did. So some chances of pregnancy are there in you.
Fingering inside the vagina with semen on fingers can also get you pregnant. In this way sperms get deposited deep inside the vagina. You should avoid this in future to be protected from unwanted pregnancy
Refer to a gynaecologist for more queries
Don't worry you would be fine
Hope this information helps