FYI, you are working from the top of the tree down!
I couldn’t figure that out for a bit because I was expecting to start with the trunk. This is what comes from not reading through your pattern first.
Therefore, thinking I knew best (ummm, no), I began with the 3 stitch trunk.
Therefore, the unintended serendipity of have two additional 3-stitch green rows at the top of my tree which made a perfect patch on which to place a shining star.
All in all, resulting in peace, happiness, and two extra rows of grid at the bottom to balance things out.