Ok...I have spent more time on trying to sew jelly roll strips together today to make an easy lap quilt: however, I am ready to tear my hair out! When I sew the strips together on the diagonal I end up with one strip having a shorter edge than the other. Give me a block to piece and I am happy....what am I doing wrong? I have watch multiple You Tube videos that make it look so easy. ...but for me it's not.