It appears that problem may be in both piecing and in cutting.
So go back and measure the parts. Did the blocks finish out the size they should have. Are the triangles the size they should have been. Take off the offending parts and measure and put dots where the end of the seam should be
Accuracy in all parts is important. A recent teacher in a class said the piecing is only as good as the last seam. At the bottom it appears that either the block side is not the right size or the triangle is not the correct size.