Have you ruled out medical conditions that may be being caused by something other than your diet? You said you just ate and you still feel weak? If food isn't helping then maybe there is something else going on. By all means keep the primal lifestyle, but maybe you should see a doctor.
When I first cut grains and sugars out I was still hungry quite often for a few weeks, but it passed. Now I can definitely go with one meal a day. But typically I just eat when I am hungry. I usually eat VLC, but not always. But when I do have extra carbs (usually in the form of potatoes, sweet or regular) that's when I eat more. I'm no doctor and I am not even going to guess what the problem may be, but if I were you I might try some different supplements out.