What’s the chance...

So my cycle ranges from 28-30 days and my period consistently lasts 6 days. I had protected sex on day 8 and on day 9 but the condom broke on day 9. Major oops since I’m not on any type of bc. My boyfriend did not “pull out” on day 9 when the condom broke.

Since I don’t want to get pregnant at this point in my life, I took a plan B the next day which was day 10 of my cycle.

What are the odds that I get pregnant (I know, it’s impossible to know but give me your best guess)? Have any of you with a similar cycle gotten pregnant from having sex on day 8 or 9 of your cycle? I hope the plan B works but since my cycle varies, I wonder if I could have been ovulating on day 8 or 9 or 10 but it seems highly unlikely. Also, what are any of your experiences with taking plan B?

By the way, I am 21 and a junior in college, which is why this is not a good time in my life for me to be pregnant.

Also, I am writing this because I am the type of person to worry. If any of you have anything to add that might ease my worries, I would appreciate it.

Thank you so much to anyone who takes their time to read this.