How do I stop mispronouncing the 'tt' in words like 'dóttir'?

I’ve been recording my practice sessions, and I’m really struggling with the preaspiration of the 'tt' sound in Icelandic. It keeps coming out as a standard 't' instead of having that crisp breathy quality before the consonant. Does anyone have a specific tongue-positioning exercise, or should I just keep listening to audio samples on loop until it clicks?