6 month old doesn't roll or sit

[Toklastennis]

He seems aware and active in every other way. I give him a few minutes tunny time each day but he's got reflux and it makes him sick so he can't do it for long. I am starting to get worried now - is there anything I can do to encourage him?

Mine were more like 7 months for reliable sitting and never rolled!

Mine didn't sit safely until 8-9m by which time he was already crawling

Have you tried a Bumbo seat to help him build up the muscles he needs for sitting? They work better with fatter babies though so if yours is a skinned-rabbit type it wouldn't work as well.