have fed you with. gave you... to drink (Greek. potizo).
hitherto, &c. = ye were not as yet able to bear it. Instead of supplying the ellipsis with "to bear it", we might read "not as yet strong enough".
neither. Greek. oute or oude.
Related Commentaries of 1 Corinthians 3:2
1 Corinthians 3:2
2 I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able.