ANSWER
One possibility is to have six rows, with eight or nine stars in alternating rows...
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Of course, there is nothing that requires that the stars be in a symmetrical grid-like pattern. US flags from 1819 (21 stars), 1820 (23 stars), 1836 (25 stars), 1845 (27 stars), 1847 (29 stars), 1851 (31 stars) and 1890 (43 stars) all feature somewhat non-symmetrical patterns of stars.
WHO GOT IT RIGHT: Steve Shuba.