Need some encouragement! Darn water!!

"The only way to get better at swimming up hills, is to practice swimming up hills"

In other words, just keep working on it - OWS is nothing but a wet hill.

Maybe try rolling over on your back and floating for a bit if you feel an episode creeping up on you (heck, do some backstroke if it suits your fancy!).  The suit will keep you floating, plenty of air to catch, and in practice there's no pressure to keep moving.

As you say, your pool swimming is good; it likely didn't start that way, but practice got you there

I have spent the past few years fighting OWS panic.  THe advice to get in as much as possible this week is key.  On race day swim your own race, don't freak out when swimmers from waves behind yours pass you.  Stay close to the bouy line but in the back of your wave.  If there is an option for a different color cap to wear so the kayakers can identify the less than comfortable OWS swimmers take it.  They will keep a close eye out for you.

The week prior to my last race I was on vacation.  I hadn't had much OWS where I live this year due to the rain messing up tri club swim days.  I found a lake near my families house and went daily.  I got permission from the guards to go out beyond the roped off area, they let me have an area about 100 meters long between 2 barrels right behind the roped off area.  It made a huge difference, by race day I had no problem in my swim--a first for me.  Every opportunity to swim in a lake was taken by me.

Really cold water does take the breath away.  Get in and get used to it.  Ear plugs (you can buy at Walmat) if the current bothers you are a big help.  Those 63 cent earplugs I bought made a huge difference to me.

x2. I also second your idea of swimming in a pool with your wetsuit to get used to the compression on your chest. I strongly recommend that the morning of your race, you get in the water at least a half hour before your wave starts and just get used to the water. It's going to be cold and it's going to take your breath away but you will get used to it. It may take a while (that's why I'm recommending 30 minutes) but your normal breathing will come back. Honest.

the greatest advice i ever got about dealing with COLD water is to get your face in it.  i did the columbia tri in 2008.  it was COLD (around 64 i think).  it was a in water start and while i was waiting i just floated on my back.  when the horn when off and i tried to swim, i started to hyperventilate.  i had to do a modified, head above water freestyle for the first several minutes until i got my breath back.

i read that getting your face used to the water is the number one way to prevent hyperventilating.  the article suggested that in cold water, get in early if possible and instead of just waiting for the horn to go off by treading water, get your face in the water.  i did this at columbia 2009, granted it was not as cold, but i got in and while i was waiting i just kept my face in the water.  in the 2 minutes or so we had to wait for the start i got my hyperventilating over then and by the time to horn went off I was fine.  if you can't get in before, maybe just splash your face a lot.  it worked like a charm for me.