Dear Wishful Thinking, I have the same problem, often! I try very hard to measure and cut accurately. I have a 1/4" foot too. But then when I sew my blocks together and start adding sashing, they never match perfectly, which drives me crazy. I always have to go back, unsew and resew to get them to line up correctly. When I've asked others why this is happening, they tell me when they cut and sew, it just all falls together right, if you've cut and sewn accurately. I am actually glad to read your post because it makes me feel more normal.
Sometimes I get so discouraged, I just put it all in a box and put it away until I can handle working on it again.
You are not alone and we who struggle also feel your pain!!!