That is way too much! Only reason would be if the pattern is some sort of bizarre fussy cut thing. The way to figure it out if you are a visual person is to cut out a block on paper and then use the pieces (with seam allowance) to lay out on a yard of fabric. See how many you can get from that yard and then multiply by the number of blocks needed. Even for a plain backing - 68 x 90 - you could get by with 2 pieces of 42" fabric that are 2 3/4 yds long. So you could use as little as 5 1/2 for backing. Using this idea 14 1/2 for top is nuts!