I need an urgent answer here..

I will follow the question structure used by Shepherd999 in another topic to provide my information.

1. What worries you specifically (and why)?

My girlfriend and I were having some fun and we masturbated and semen came out. I'm not sure whether there was semen on my hand, however I wiped off everything with a tissue. Then after about 5 minutes we started having some little fun again and I was trying to touch her clitoris with the same hand I used to ejaculate.

2. What part of her vagina did you touch? Do you mean her vagina, or her vulva, or what? 

I'm not sure. This was our first time and she didn't even let me see her vagina, vulva or whatever. She was wearing her underwear and I was just touching the underwear (didn't send my hand inside and move the underwear) The underwear was thick and I didn't feel whether she was wet (She's also not sure, but she thinks she was wet) And the wetness had not reached underwear because of the thickness in underwear. I think I found clitoris and she was getting aroused with that..So basically, I touched only the underwear and around clitoris with semen-wiped off fingers.

3. With what did you touch it?

Fingers, as I can remember, Middle finger and index finger

4. Did you touch through or under the clothes she was wearing?

No, As I said, I didn't remove the underwear. Everything was done from outside.

5. What date did you do this?

Yesterday (about 17 hours ago). Additionally, she had a body was after about 40-45 minutes from the moment this occurred.

6. What date did her last period start?

About 3 weeks ago

7. How long is her cycle (typically 28 days)?

She does not have regular periods and the last time it happened around 3 weeks ago. And that too after a period of about 3-5 months as she claims. 

The question I have, should she use Postinor 2 in this kind of a situation? She's confident that nothing wrong occurred and with irregular periods, can Postinor 2 have side effects?