Help! The dryer's shrinking my clothes.

Every pair of pants that I buy becomes too tight after a few months.
To avoid the most obvious conclusion, I theorized that the dryer must be too hot, and it was shrinking everything. I also have a tendency to buy tighter clothes when I feel more confident in my appearance, and looser clothes when I feel fat and frumpy. (I even buy smaller or larger shoes.)
But last week I went to Eddie Bauer to buy some new pants, and the only ones that fit me comfortably loose were size 12! There's nothing wrong with size 12, but that's the size my mom wears!
In 2003 I could squeeze into a size six. I was even forced to admit a couple years ago that size eight was unflatteringly small. Then I promised myself last year that I couldn't buy any more size 10 pants. Instead I had to use what I had until I could fit into an eight again. And now size twelve! Nooo!