You did'nt say your level so I going on pure guessing here, but this is totally wrong (in my personal opinion) unless you want to run out of ammo on bigger fights fast.
Personally if I see the tank has pulled too much or is taking a beating (same applies to 4X) it's Kolto Bomb (talented for +healing) > Adv Probe (again talented for....) > Med Probe (seeing as it only costs 1 ammo with talented Adv probe). Then do what ever is required including another Med Probe as you saved ammo from casting Adv 1st. Also, make full use of the 30 charges and use it every chance, the regular Med Probe can be specced to give you 6 stacks per cast so it builds back up in no time at all.
Dont forget that the more ammo you have, the better your regen is. Talenting and making use of talents / procs that drops costs makes a massive difference between having ammo to heal the whole group or failing the fight.