Granted i am not using 'proper' monitors, i use my marantz pm4000 amplifier and mordaunt short speakers, also use my Klipsch S4 earphones, i also have listened to the audio through my iMac speakers for comparison. I do understand that these will colour the sound but all outputs seem to suffer from the same problem, but it's high end stuff. I did have some M-audio monitorsa year or so ago and the sound was so uncoloured and dull that i got rid of them, thinking they were the culpret.
Time to start doing A/B testing.
You'll need another audio interface to use.
You might try another microphone as well.
Test each mic with each audio interface and have a listen.
The other alternative is you are so used to listening to audio that has been jacked up, that a true flat response (ie, no tweeked frequencies) doesn't sound normal any more. When that happens, reference monitors certainly won't sound "good", but they will sound like what was recorded. which is the whole point of having them in the first place.