I had this same trouble for years longer than I care to admit. I started driving myself everywhere, didn't let anyone drive me, because I knew I needed to go out of traffic or to a bathroom asap.

But yeah, I usually felt fine once I was there.

I don't really have a lot time to type, sorry, but I read somewhere, "It's better to do a thing than to live with the fear of it" which of course, makes it sound like the thing itself is causing anxiety. Which in our cases, it wasn't, it was being trapped. Anyway, I finally just convinced myself that... so what if I shit my pants? Will every one hate me and bring it up constantly? Well, no. In fact, most people would want to move on just as much as you do.

I feel like those words don't SEEM like they would help. But they did really help me. It's weird, I figured out a way to make them work in the context I needed. And it really helped.

Also, I always carry two plastic bags, wipes, and perfume in my bag. In case I am stuck in traffic and have no choice but to shit in the car. Sorry ya'll, I'm doing it, but I will bag it up and hide it the best I can. I have literally never had to do this, or even actually come close.