Your blocks look great. Whether you piece then conventionally or paper piece then you will have the same issue. I just did a Storm at Sea topper and I ironed all the seams open. My DH took a closet pole and ran it through the table saw and took off about 1/3 of it so the pole sat flat on my table. I place the right side of the block down and use that iron on. Works great.
Also, in order to get my points spot on, I put a pin at the tip of the point I wanted to match and then through the point where it matched on the other block. Then as I held that pin vertical, I put a pin next to it ti hold it in place.