Mistweaver Monk heal spam macro help

Hello everyone, i am trying to set up my mistweaver monk healer to be able to spam heals for my team while i spam my dps macro on the rest of them without her going oom. She is currently level 85 and well geared, and atm I am primarily doing battlegrounds with 3 disc priests and a mage + this monk.

My primary question is, if possible, how could i set up my Surging mist to cast only when it is instant? I have the glyph for it to automatically heal the lowest nearby friendly but it's too much mana to spam and i only want to use it when vital mists reaches five stacks.

I'm guessing using a macro like:

/cast surging mists
/stopcasting

Would work, but when i put this in my spam button it would stop all casting. Any suggetions?

Do you use Jamba? Just a suggestion but you could put surging mists on its own hot key and only hit it when Jamba-Proc tells you.