The total virtual memory size is the sum of the virtual size of all processes. Note that (1) much virtual memory is shared between processes because they use the same libraries, frameworks, etc and (2) just because a memory object is mapped to the virtual adress space of a process, it doesn't have to be allocated in physical memory or even be in a page file.
So that's what I understand the "total virtual memory size" is. A quite uninteresting number if you ask me.
I can't explain why the number should change if you display "number of ports" though.