This is my first try at a carpenters star block. I'm also inexperienced with piecing. I have two questions. There's some puckering going on in the half square triangles. Is there a way to avoid this? Also, how do you cut down on bulk on the back where the seams all meet? There are like big nubs back there. I'm going to try to post a picture but it's my first time trying that too so I hope it comes out. Thanks so much!