Unprotected sex with the outside of vagina in 10 sec!

Dear Doctor
First of all, thank you for this outstanding service!
Here is my story
A prostitute massaged me and did a blowjob with condom.  I guess that should be no HIV risks at all.
However, during the massage the prostitute climbed" over my body.  She was rubbing my unprotected penis against her vagina. There was a little erection with my penis and her vagina is really wet. I think there was a little penetration ( the head of my penis is in her vagina for 2-3cm and last for 10 seconds ) . Afterthat i washed my penis with water right away.
Anyway, is that a possible risk ? Should i get a test ?  
Kind regards
DDH ( From VietNam)

[LIZZIE LOU]

you THINK there was a little penetration?  is this your first time having sex?  

you either entered her or you didnt?

[vietnam1]

I think there was a little of penetration because my penis if a little bit erect , and her vagina is really wet. So when she was rubbing my unprotected penis against her vagina. The head of the penis is in her vagina ( only 2-3cm) and last for few seconds .
Is that a possible risk ? and if it's a risk, should i use PEP ?

[LIZZIE LOU]

wow...

you being "erect" and her vagina being "wet" does not mean you penetrated her.  

FULL PENETRATION IS REQUIRED FOR TRANSMISSION.