I can tell from looking at the last picture that the square in a square block is not square. It looks like the point areas of the pink are larger. Perhaps your seams were not quite a full 1/4" inch. But it looks if you took a smidge off those areas, it would bring the points closer to where they are supposed to be. When you are adding the triangles to the square you have to be VERY careful not to stretch the bias, or you do get these wonky squares. That being said, as a beginner, your work looks very nice, and those little point issues won't affect the beauty of this quilt.