I know this is a long shot, and I lean toward the growing gestation as a
reason for the 6 mo. old to figit at feeds but...... Purely anecdotal......

     I have three children now 5, 7, 9 ( everytime a child began to switch to
primarily solid -  I conceived ).  The first and 3rd baby would never just
sit and nurse at the breast, even as 1 and 2 mo olds,  they released and
would relatch often, apparently distracted while feeding, except for those
very sleepy early and late feeds.
     The middle baby would very contently suckle for 25 -40 min. , finish her
"meal " and then doze off to sleep. I thought there was something unusual
about this baby, she was so still and content.
     The end to this long story is that the 1st and 3rd baby are both very
strongly ADHD ( attention deficit - hyperactivity disorder ). Everything they
did, even as small infants, was in short easily interrupted burst. These were
newborns who could scoot themselves from one end for a crib to the other
during a 1 1/2 hour nap they were so active.
     All my " checking " into the condition shows there is a chemical (neuro
- transmitter type ) imbalance or difference in these children.   And my
experience is that it certainly shows up at a verrrrry early age.

Paula Ray RNC, IBCLC
Longview, Texas