Great advice from everyone. Interesting - my mom is an accomplished sewer but when it came to quilting she was ready to let all of her equipment have a fatal accident. I asked her what was frustrating and she said that she ended up with wobbly seams, nothing lined up right, couldn't get intersecting seams to match - sound familiar? So I said - Step away for a while. Pick an easy pattern (she wouldn't though...)
Then I suggested 4 other things:
1. DON'T STEAM when you press.
2. Use sizing or spray starch on the fabric
3. Don't prewash the fabric
4. When sewing intersecting seams, pin on either side of the seam to keep it from moving.
She tried it all and eureka! Matching seams, no wobbles and much less frustration.
Sometimes its the little things that work best! Our hugs to you though even if you never quilt again!