T.B.
S.,
I have an almost 3 month old and I notice that sometimes our feeding sessions turn into a "mouthing only" session. At that point, I end the feeding. Of course, my son is above the scales on weight gain, so I don't have to worry about him not getting enough nutrition. If you are in a similar circumstance, I would suggest that you end the session and feed your son when he is hungry.
Best of luck!
T.