Zika - Caribbean - anyone got Docs letter

Katie
Hi, 
I booked a holiday last week to the Carribean. Now kicking myself I didn't think of this before but it's in a Zika Affected area and I think the advice if you're TTC is not to go. I really don't think it's worth the risk and we've paid in full. 
The travel company won't change our holiday without us losing 70% of the cost because we're due to go in 6 weeks time. 
They said the only way they will waive the costs is if a Doc writes a letter to say we're trying and that we shouldn't travel. Called the docs and they've passed it to another nurse who isn't in until next week. 
I'm worried sick - has anyone been in this position and a Doc agreed/refused to write a letter? 
Many thanks 
Katie