You are comparing it to Bard now and it is a known issue that because they don't have to worry about moving and not being able to deal dmg like most DD they can have higher output.
Though to be fair DRG has a slight edge, they have jumps and also Piercing Talon, they can fight from afar or on the run if needed so if you haven't add that to your rotation you might want to give it a try, since every little bit of input helps. Can also consider how often you use Invigorate, it's 500TP regain is decent so if you find yourself not using it often or at all then you can try out Piercing Talon as an on the run WS when you are unable to get within range of the boss.
And, people are just trying to give input, it doesn't help to call the rotation "not rocket science" if you can take the time to give a detailed explanation over your rotation it is possible that there is something you are doing that's causing you to lose dmg output. Such as you don't explain when you use Life Surge for an ability which grants instant critical, you don't relay if you have ever tried it on Chaos Thrust or if you have also saved it for Full Thrust.
You don't explain how you keep the DoT up, do you time it so that all your buffs are up such as you open with, Heavy Thrust, Impulse Drive-Disembowel, Blood for Blood-Life Surge, Chaos Thrust, Phlebotomize, Heavy Thrust, Vorpal-True-(maybe you Life surge here)- Full Thrust. etc etc
It's simple enough to say you put the buffs up but if you don't explain the exact rotation players can't help you in determining whether or not you are utililizing them for maximum potency. And of course I know there are also jump abilities and such but being as I'm not a DRG main I'm only taking a stab over what a maximized dmg rotation might look like.
Also while you might see the MNK DoT as "stronger" DRG's are actually stronger when you take base dmg into account, since MNK DoT base potency are 0 and 40 while DRG's base potency are 170 and 160 which give them an edge compared to the MNK's DoT.
MNK DoT overall DoT is about, 250/240
DRG's is 290/360
With greased lightning III, Touch of Death can be comparative to phlebotomize but in the overall scenario DRG has the edge.