I visited my bf on 24th oct.....my lmp was from.20-23rd oct......by mistake his ejaculated near my vagina....not in my vagina.....but outside .....as a preacaution I took unwanted 72 (an Emergency Contraceptive) on same day...

Dear Anon,

If you can only become pregnant if you had intercourse and he ejaculated inside you.

The most common side effect of an emergency contraceptive is changing the woman’s cycle. Here is a complete list of its side effects:
Side effects may include changes in your period, nausea, lower abdominal pain, fatigue, headache, dizziness and breast tenderness. Some women may have changes in their period, a heavier or lighter next period, or a period that is early or late.

This is strong medicine and is only to be used in emergencies.
I would suggest getting on a regular birth control if you do wish to engage in sexual intercourse.

Here is an article from the EmpowHER community with facts about ECP. https://www.empowher.com/birth-control/content/facts-about-emergency-contraceptive-pills?page=0,1

We also have a whole section in EmpowHER on birth control .

https://www.empowher.com/media/reference/birth-control-center

Best,
Helena