I felt my baby flip from breach to head down at about 30 wks. I could see bumps sliding past under my skin. : ) I didn't feel the baby flip back to breech at 33 wks, though, but I did feel the baby was sideways at 32, so I wasn't too surprised to find at my mw visit baby was breech again at 33 weeks.
Movement can be helpful, but I have trouble visualizing position from that. Also, the first time baby was breech I had kicks on my ribs, but it was because baby had feet up by the head!
There was a thread somewhere around here recently about feeling the difference between head and bottom... I think the consensus was that if you gently wiggle/push the head, only that moves, but if you gently wiggle/push the bottom, the whole baby moves. I still have trouble feeling the difference, but that is how my mw tells position, and then confirms it with heart tones.