I play an Operative healer, levelled completely in pvp: If you have a person on you that knows how to use there interupts, stuns, CCs etc - He will eventually take down anyone; its the whole point of having them.
Kolto Probe inst really designed to be a huge heal; Its main purpose is to proc Tactical advantage to use Surgical Probe and Stim Boost. Used correctly with your AOE and Single Target stuns makes you a true pain in the backside to kill. Learning when to use your mitigation skills comes with practice; as does knowing when to get out of dodge. In my opinion, team an operative up with a Tank class for the guard and used correctly the operative will top any healing chart going.
Keep plugging away mate, Try not to get too frustrated with it.
Medíc.