Maybe your 12 lb base weight was an optimistic illusion! Are you sure you counted everything in the past? Are all those little things in your pocket now counted as base weight?

I found that weighing stuff is variable. I have a good postal scale, yet I get slightly different weights each time I weigh stuff. Of particular note is larger stuff that can ooze off the weighing tray reducing the weight. I also found that if the item is centered on the scale, it does not weigh accurately. I have the opposite - stuff weighed years later weigh less!

Have YOU increased in size? If so those clothes, the next size larger, will also weigh more.

If you are use manufacturer's listed weight, often this is sandbagged to the light side. Tent is a perfect example. The tent has to include everything you use - strings, pegs, ground cloth if you use it. Most "weights" stated for tents are bogus. Sleeping bag - got to be stuffed so the weight really should include the stuff sack. Shoes are another example - often the listed weight is of ONE shoe - now who only wears one shoe!

Theoretically, based on the amount of lint I clean out of the dryer, clothing should weigh less as it is washed over and over. Hey, if you never wash anything, and dirt collects, over time it weighs more!