I come from a similar place, I don't think that I can handle my most powerful fantasy. I also worry about the health risks of consumption.

But I see a couple of problems with your idea. One is that most mistresses would not want to inject a batch of foreign material into themselves. And to me, it would be sort of a buzz kill if the dominant mistress would do such a thing on my behalf.

Also, you are still going to have to deal with fecal material unless it was a super efficient enema.

Where I come out it, I would prefer that she just goes on my face, the old fashioned way. No ingestion. I can get a real buzz out of her laughing while my I lie there with my face covered.

One time, with her shit still streaking my face, the mistress ordered me to come with her into the bathroom and I was told to clean her ass until it was spotless and passed inspection. Then, and only then, could I tend to the fact that my face was streaked with her shit.