1. If your fresh water tank if filling while hooked up to the spigot, it's usually caused by the knife valve getting bumped while moving stuff in that compartment. Mine is in the bay with the electrical cord and I've bumped it partially open on occasion. Find that valve and make sure it's closed.
2. A few things will give you better "pressure" in the shower. One is the small hose screens used to keep debris out of your system. You'll find them in the end of your water hose, at the connection where the hose attaches to your rig and in the ends of the faucets and shower head. Since yours is a 2015, I would suspect all of those screens are clean so file this away for future reference. That said, your system is designed to "save" water so your shower hose/head will have a small disk or washer inside the hose or head to restrict the flow of water. Remove the hose and the head and remove any/all washers/restrictors and reassemble. Then check your water flow. If it improves, you're a hero in your wife's eyes. You can also purchase a Oxygenics shower head. While it does not offer extra water flow, it mixes air with the water to give you the feeling you have extra pressure. Finally, remove the water pressure regulator and see if your flow increases. If it does, you might want to change out the regulator if it's not adjustable. If it's adjustable, increase the pressure to 55-60 psi. If your regulator does not have a gauge built in, you can buy one at Home Depot for less than $10.....Dennis