Hi, Daily Alice!
There's nothing wrong with your current developer.... You just need to be aware of how many prints you are making per quantity of the solution. In tray, it degrades pretty fast. Uncovered, it'll be basically gone in 24 hours even unused. If you cover it with saran wrap, making sure the wrap is making full contact with the liquid (not taut over the lips), it'll actually last for a few days. Making 11x14, it's easy to get carried away (and I do the same!) and start exceeding capacity.
I mostly use Dektol but I've noticed, adding concentrate after exhaustion doesn't really do the same thing as tossing bad and making a fresh working solution. I really don't know why.... So when I start seeing problems, I either call it a day or start over with a fresh mix.