First I will share that I am a hand quilter and not a fan of machine quilting. There are some beautiful machine quilted pieces but why did I go to all the work of piecing, only to create another design that does not compliment my own work, which took hours to create?
That said, take a look at the recommendations for quilting on the batt you have chosen. 8 x 8 will probably leave some big spaces that are bigger than recommended. Usually recommendations are for no larger than 4" apart. I have done stitch in the ditch--it's a lot of work but doesn't show! I have also done 1/4" from the seam and it can be seen while complimenting your piecing. If you choose, you can put another design in the open spaces or simply echo your previous stitching to compliment the design of the quilt.You may find you want to combine the 2 methods, using stitch in the ditch for holding some of the quilt together but then use 1/4" from the seam as your complimenting feature. Even a box within the 8" square might be pleasing?
You have a beautiful keepsake. Wow, for your first quilt, it is amazing. Enjoy it in years to come!