Can I take plan B while ovulating?

It’s my 3rd fertile day and I was having sex with my boyfriend and he came inside the condom but when he pulled out it fell off inside of me so I want to take a Plan B just to be safe but I read that it may not work cus I’m ovulating?? Please help I’m anxious and scared and confused I don’t know what to do I’m 15 years old I cannot get pregnant