The problem at hand is, that jobs are focused for a main task while classes can be used to be more of a hybrid and can help to expand your abilities towards the other roles at the price of efficiency in your main task.
So basically what you are doing is making the other dps work harder (since someone needs to compensate for the dmg you are not doing) to slightly carry either the tank or the healer. The thing is you are not gaining any significant boost in your healing or tanking capabilities for the price in dps you pay. Your heals are basically the same and a titan egi is a better tank than topaz carbuncle, not even mentioning that you are basically making the tanks job more difficult, since a tank pet deals less damage and is more difficult to hold hate against.
If you actually wanted to be a good hybrid, it would be much better to go either tank or healer and work on maximising your dps. For instance the healing requirements in wod are so low that a SCH's fairy can solo heal most of it, while both healers are in cleric stance dpsing (thats basically what i do on my SCH in WoD).
I am going to be brutally honest here with you, it seems to me you want the nice feeling of having contributed to the groups success but dont want to be responsible if anything goes wrong (helping heals but dont want to be an actual healer). If you wanted to be a hybrid, cue as SCH or WAR and have fun.
