Take my "advice" with a grain of salt, because I've had a strong germ fear to the point I couldn't care for my pets and had gone seven years without taking out the trash but without being OCD, so I may not be of any real help. But I do sympathize!

The counselor might be on to something with the exposure therapy. That is how I got over my germ fear, slowly but surely touching things and refusing to wash my hands for a certain time. Perhaps once a day go to the library, sit at the table and put your hands on the desk for five or ten minutes without letting go of the table or going to wash your hands. When the ten minutes is up, go wash your hands. And then make it fifteen minutes touching a used book, flipping through the pages and touching all over it, then when the fifteen minutes is up wash your hands. But bring a timer with you and set a time so that you know you cannot wash your hands until the time is up. Try doing the same thing with charcoal. Realize that charcoal is not dirt or germy, it's "just a messy rock". Sometimes knowing that it's not real dirt or real germs than it makes it easier. With a fear that severe I don't know how likely that will help, but that's how I overcame my phobia. I hadn't touched a garbage can in 7 years. Then I decided to try touching the garbage can and then washing right after, then I tried touching it and then only using hand sanitizer, then after I became confident I took the trash out to the bins and emptied the garbage out. Once I did that a few times I became confident and only wash my hands if it's the wet garbage.

But I think exposure therapy, even if it's only for five minutes, can be really beneficial to you. It may not "cure" this fear, but it may help overcome that fear.