How to find a list of all program heaps on Windows?

Question

In trying to experiment with stack vs heap allocations in a C++ test program, I was first surprised to discover that Windows does not necessarily situate the stack at high addresses and heap at low addresses. On digging deeper, I was further surprised to discover that it maintains several heaps, the details about which can be ascertained programmatically as shown here. So I have now in my test program (on Win10, x86-64, mingw73_64):

int main(int argc, char *argv[])
{
    // [GetProcessHeaps code copy-pasted here from the MS link above]
    // . . . 
    // . . .

    int* ptr = new int[64];
    qDebug("int array malloc addr in main() = %p", ptr);
    delete [] ptr;

    // New type that does nothing interesting other than debug prints in ctor/dtor
    Foo* pf = new Foo();
    qDebug("Foo malloc addr in main() = %p", pf);
    delete pf;

    return 0;
}

[The qDebug is a Qt function, not relevant to the present problem.] I had expected both allocations to get fulfilled from one of the program heaps. Instead I see the following:

Num heaps = 3
Heap 0 at address: 0x750000 - 0x777000, size 159744 bytes
Heap 1 at address: 0x10000 - 0x20000, size 65536 bytes
Heap 2 at address: 0x1c0000 - 0x1c8000, size 32768 bytes

int array malloc addr in main() = 0x1c64b0

Foo alloc addr in main() = 0xc673920

As you can see, the int array allocation gets fulfilled from Heap 2, but the Foo allocation is out in left field somewhere. (Heap sizes obtained from code here.) Repeated runs yield different addresses, but the results are similar (have also seen both allocations come out of the "fourth heap"). Are there yet more heaps beyond the three printed by the MS code? Is there another method to get a comprehensive list?