Am I pregnant?? Please help me guys!!?

Hi, I'm 17 years old. I'm worried that I may be pregnant.
I have an irregular menstruation cycle. I haven't had my period since Oct 15.
Last week, I had unprotected sex for about 5-10 seconds multiple times. He stuck it in and then pulled it out very quickly. He said he was not close to ejaculating. Other than that, we used a condom and he did not really ejaculate inside me even with a condom on.

Given that I have an irregular cycle, what are the odds that I'm pregnant? When should I take a pregnancy test?

Guys, thanks ahead for your advice!!