I see nothing at all "wrong" with your star block. It just needs to be squared up. You have left enough room to trim and not end up chopping off points.
But, here's just a bit of an idea/suggestion. If you are going to be really precise/picky, take a look at the cross-wise vs the straight grain. If you are joining cross to straight there is opportunity for the cross-wise to stretch ever so much and create some wonky appearance. Try to join straight to straight and see if it makes a difference for you.
Love the pattern you found in the magazine and want to make! Great pattern.