Sometimes from 22 yards away it will go 28 with 18 yards power, other times from 22 yards it will go 16 yards with 22 yards power. Same like, similar green.
This is very strange, given the quality of the wedges you have. I only pitch with my 64° wedge and find it very consistent. Are you using the same ball and amount of spin every time? Spin makes a big difference when pitching, once you get a feel for it you can use it to good effect but I'd start out always using the same until you get your distances spot on.
Elevation also makes a big difference. If the hole is well above you you'll usually get more roll out, the opposite is true if the hole is below you. Watch for whether the green is sloping towards or away from you though. A green that is sloping away will mean the ball rolls out more, it'll stop very quickly if you're playing into an uphill slope.
Try to persist with it, the pitch is a very useful shot.
chipping is hard because the green affects it so much.
I almost never chip for exactly this reason. With a pitch you only need look at the slope close to the hole, with a chip you need to think of it almost like a putt. There are fewer variables with a pitch, this makes it easier. In my opinion anyway.