Welcome! It is rather difficult to get your stitching on the top to match something on the backing. If you really want it to match, either sew the next set of rows from the back or stick a pin from the back to the front where you want your line to be, and mark it on the front. Use the marks to plan your stitches. Make sure you use an appropriate fabric marker and test it on a scrap of YOUR fabric to make sure the marks will come out.