Not sure about your slow water, other than, maybe a line is pinched somewhere causing a blockage.
But in the mean time, RV toilet flushers work one of two ways: A pedal that pushes down only, or a pedal that pushes both up and down.
The down only pedal: You can press the pedal slightly and start the flow of water without releasing the valve in the bottom of the bowl. This will let you fill the bowl with water before letting the valve open. This helps get "everything" down ... especially if your water is slow.
The up and down pedal: If you push down on the pedal, water flows and the valve opens. But ... if you press up with your tow, water fills and the valve stays closed. Here again, fill the bowl with water before releasing the flush valve.
Hope this helps. I think you have a pinched water line somewhere.