You might want to take a look at this.
http://www.quiltingboard.com/links-r...g-t243146.html

When I have seams that need to match up I use a little dab of Elmer's Glue on the seam. This alleviates the pins and my seams match up.

I found "fork pins". They are pricey, but, I can sew right up to them & pull them out. Perfect every time. They are by Clover & I got them on Amazon. Well worth the price!

I've used Elmer's Washable glue when matching seams and it works very well. But it means (for me at least) standing at the ironing board, applying the dot of glue, ironing it dry, and moving on to the next seam. If I can match them by pinning I don't bother with the glue. But you seem to be having problems with the pinning so you might try the glue. Just make sure the seams really match, though, because pulling the glued seam apart is not fun, either.

I am a Virgo and therefore a perfectionist by nature, so I understand where you are coming from. That said, I quilt because I love it, and I have learned over the years that nobody is perfect, so I give myself some slack on being "perfect". Pressing seams to one side on one row and the opposite in the next row usually gives me good results. I haven't tried it, but I saw a quilting tutorial where a pin was placed straight up, making sure it went 1/4" on both sides, then pins placed on either side to stabilize the piecing and that seemed to work. The Amish deliberately leave a mistake in their quilts, as only God is perfect. Fortunately for me, I never have to deliberately leave a mistake. LOL. Just be patient with yourself, perhaps basting just the place where pieces come together, then checking and if all is well, sew with a regular stitch.

NJ Quilter that is exactly the same way I do it, I never seemed to be able to nest my seams when pressing to one side,open seams are great when you have points of a star coming together.

This is how do it.

I am neither expert nor perfectionist but here goes. I have a lot of trouble matching seams on my rag quilt. They're so bulky. I saw on SWN a tip she Gave. In addition to pinning on either side of the seam and nesting try a u shaped pin (tidy pin) for both sides of the seam with the same pin. They're inexpensive from WM or JF. Pinning either side worked pretty well on the last rag quilt I made but I'm going to try the tidy pins next time.

I am going to side with the "try not to be a perfectionist" group here. If you keep that up, you take the fun out of what your doing, and when you do that, you just keep more mistakes, and then pretty soon, you have put what ever your working on over in the UFO pile. Making quilts is supposed to be relaxing, fun, enjoyment, etc... try the suggestions above and they are sure to work, but don't fret if one is not perfect : )

Double check your blocks to insure they are all the correct size. This will definitely help when lining up blocks and rows.