Okay, so I tried it again tonight but with a fresh cake of soap and a stoneware mug. It went much better this time. I'm still not working up as much lather in the mug as I used to (I'd also like to note that I've switched bathrooms, and the humidity and temperature are really weird in this new one, but that shouldn't really make a difference, right?) but I worked up as much as I could, and then just a few seconds of work on my face and I was getting thick, if not necessarily voluminous, lather. I'm still having a problem getting the lather to stick around on both sides long enough to shave; I usually have to just lather one side, shave, swirl the brush around for another 30 seconds, then lather the other side and shave it.
I've definitely been considering upgrading to badger, I just can't afford it right now. Prom and everything, you see ($250 for two tickets...yeesh.) But I'm sending my razor off to be sharpened (I'm getting sick of the shavette) and as soon as I can, I'm gonna get a nice badger brush. How's the Vulfix 662? I'm quite fond of pewter and it's both their highest grade and a quite reasonable price (can someone explain why it's noticeably cheaper than their other brushes of the same grade? I checked the bristle loft, it's not small or anything compared to the others. And shouldn't pewter be more expensive than plastic?) I've also heard of people adding a few drops of glycerine to their soaps to increase thickness. I'm gonna drop by the drugstore when I can and try that.
And I gotta say, I can't thank you all enough for being so helpful. Working up a lather is the one thing I still haven't gotten any sort of consistent control over.