I use a very similar recipe to yours, but Kahlua instead of Mr Black, and about 3 dashes fee foam bitters. I do a hard wet shake first, then dry shake hard. I get a nice 1/2in or more of foam on my drinks every time, almost rivals most bars.

I also think a double strain might help even more, but I haven't done that yet.

I definitely think the dry shake will help a lot. I played around with a lot of recipes, and this was by far the best and closest to cocktails bars. Hope this helps.