I can only empathise 
I was in a similar situation a few months ago, only I was using aPC and had deleted what I thought were duplicate images (of a trip to Paris ironically enough!)
I actually then went on to do a bad thing, I downloaded "Recover My Files" and illegaly obtained a serial number (yes, I had no shame, just desperation)
it worked and ever since I back up everything religiously.
Just wanted to send you some hope vibes, I REALLY hope you get them back, if you fail to recover them from the drive, try the same thing on the camera card, they may be recoverable from there
I was in a similar situation a few months ago, only I was using aPC and had deleted what I thought were duplicate images (of a trip to Paris ironically enough!)
I actually then went on to do a bad thing, I downloaded "Recover My Files" and illegaly obtained a serial number (yes, I had no shame, just desperation)
it worked and ever since I back up everything religiously.
Just wanted to send you some hope vibes, I REALLY hope you get them back, if you fail to recover them from the drive, try the same thing on the camera card, they may be recoverable from there