If you're throwing with a lot of arm, "strong arming", then these distances aren't surprising to me. When I was really strong arming I was in that 240-250' putters, 270 mids, and any drivers from Leo to Valk were 285-300'. Nose up is part of it too, but honestly the gap there which surprises me most is the only 10' difference between putters and mids. 250' with a putter is good, I would think a mid would go at least 20' more.
When people are capped in that 300' range then anything with a fairway shape or more tends to get stopped at that max range, and putters and mids can creep farther than 250' the more confidence you have throwing them.
I'd look at nose down flights first, and also see if you're really strong arming the disc...like trying to throw real hard from the top of the backswing forward. Rather than letting the body turn and bring the arm forward before you start swinging outward.