Thanks so much for reaching out! I'm sure it's not easy to be in a time-sensitive situation like this.
If you're taking the pill correctly (on time, at the same time everyday), then Plan B will not do anything that your pill already doesn't do more effectively, so you don't need to take it. Is there any chance you may have forgotten or missed a pill recently?
It was definitely a good decision to stop just in case when you saw the white substance. One of the reasons people recommend using condoms and not relying on the pull-out method is because there's a substance called precum or pre-ejaculate that penises can create during sexual arousal (while erect, before the orgasm) which can contain trace amounts of sperm. Condoms can protect you from that!
Even when you're on the pill, sex without a condom can be risky from an STI-transmission perspective. You may want to consider using a condom in order to prevent STI transmission even when you're in a relationship. If that's something you want, how do you feel about having a conversation with your boyfriend about it?
I know it can be awkward to step out while you're starting to have sex and you realize you've run out of condoms, but it's totally okay to stop and quickly run out and go buy one from the nearest corner store!
Hope this helps!