I feel your pain. but it takes a big error for me to rip, so I just keep the small errors and put them together. sometimes you can fudge it a little in the seam alloances and noone will know the difference. I'm wondering about your ironing technique, esp as you say all your 1.5" sewn-together blocks turn out diffeerently. if you feel like you are sewing them the same, are you ironing them the same? I hate pressing my seams open, but it does provide more accuracy, since you may get an overexaggerated bump or a skew in the fabric when you press to the side. If you are frustrated with the block swooping down on the far side, then maybe this will help