Should I take plan b?

So me and this guy kinda hooked up last night. We were going to do it but noticed that he didn’t have a condom. I don’t do it like that so we didn’t actually have full on sex. His dick was close to my vagina (NEVER WENT ACTUALLY INSIDE). I’m just worried that he might’ve had pre cum and it touched my vagina.

Also, I ended my period a day before this happened. I had a creamy white discharge yesterday before going out with him. Does that mean I’m fertile? The app says I have 4 days until my window opens so idk. So I go take plan b?? Or don’t do anything? Would the chance of pregnancy be lower ?

Thank you!