You can stand right near the edge of flank/rear lines to stay close to group. Most fights that actually require you to stack have a predictable mechanic for it too so it's not a big deal if you are off to side a lot.I feel like my DPS is poo as monk because of how many positionals I miss. It's half me still getting used to the crossbar layout and half being afraid to actually go to the flank in some bosses while everyone is gathered at the rear, but still a fairly large DPS loss sometimes.
That said, another thing that could affect dps for physical is missing auto attacks. If you are on controller with legacy camera this is especially bad and easy to mess up. The game is really picky with auto attacks, if you aren't facing perfectly it will not go off, so you need to either strafe properly(difficult on controller with legacy) or use lockon so it autofaces you to target 100% of the time. It probably sounds/looks minor but auto attack is a huge chunk of dps for melee/bards.