I ended up having both girls with me as I visited the midwife last Friday. Luckily, Kiddo is always a sucker for new toys and books, so was thrilled with the box of toys aimed at one-year olds. And Babs is always with me, so that also wasn't such a big deal. (Providing a urine sample was more interesting than I hoped though.)
At the end of the visit, after discussing my various concerns (nothing out of the ordinary for an "elderly multigravida"), we listened to the heartbeat.
A strong beat sounded the moment she pressed the little instrument on my belly, then almost immediately disappeared.
"Third child," I explained. "It already knows that if there's any pressure there, it's time to retreat to the back."
We heard him/her moving around quite a bit, kicking a few times, and eventually got the heart beat back, briefly.
***
I have started feeling it, occasion gentle pokes from the inside (after all, it's only about 5 inches tall). I had forgotten the problem with early movement though - it makes me feel extra sick to my stomach.