Your blocks are nice, great job lining up those stripes!
Y seams are not difficult. Preparation is the key. Using a ruler place a dot at the 1/4" spots at each corner. when sewing the first two pieces together stop exactly on the Dot. Then when you add the third piece start by lining up/ matching the dot on the new piece with the dot on the second piece and pin, sew the seam, stop at the dot, then you can stitch the final seam again pining at the matching dots. All done
