I would have thought nine would be fine for this size board.
I guess because some people consider 9 stones handicap too much for such a small board (not that I would agree; I've given up to 8 stones handicap on 13x13), but if you look at computer programs such as Many Faces of Go and a few others they do place nine points on both 13x13 and 9x9.
Historically, even the 19x19 boards only had 5 star points, as seen here: http://www.haww.gov.cn/admin/upload_file/img/2006-06/1150081627576.jpg (The exception would be the sunjang baduk boards of course with 25 points - http://images.boardgamegeek.com/images/pic204691.jpg - but then again all those points were significant for initial starting position and placement of handicap stones.)
The earlier 17x17 also had five. http://www.yutopian.com/go/gallery/trock.html You can't quite make them out on that picture but I saw a larger version of it somewhere and there's five of them, on the 4,4-points and tengen (some ornate little pattern, not the usual dots).