Okay, after reading through everything I could get my hands on regarding SQL memory, I think I've identified the culprit. Per VMware's recommendation, I had enabled large page allocation. However, what they fail to mention is that one very large consequence of this is that dynamic allocation of memory to the buffer pool is disabled, and that what SQL can allocate at startup is what you get. It looks like my instance of SQL Server was only able to grab enough memory to allocate 5GB to the buffer pool, hence the odd looking values in the DMVs. When I disabled Large Page Allocation and restarted SQL, the amount of memory being used by SQL climbed to the max, and the buffer pool almost tripled in size.

Guess I learned a lot today 🙂