I wouldn't cut out PWOs all together as there are some other ingredients in them that are very beneficial. Perhaps just go with non stimmed PWOs like Megatron, High Volume, Hemavol, etc.
Do you have ADD or ADHD OP? If so, obviously people with ADD react differently to stimulants. My son has it and we give him just a tiny bit of caffeine in the mornings (V8 fusion energy) and it...
By law, I believe they have to have an expiration date. Many PWOs will clump up if not used quickly enough. Don't think the efficacy is affected though.
If you think dehyrdation may be the culprit it very well could be as it sounds like you are already questioning whether or not you drink enough water. So, DRINK MORE WATER. Also, not all creatines...