Acapulco

Tonight I made her an Acapulco. Recipe from Cocktaildb:

Shake in iced cocktail shaker & strain
2 oz white rum (6 cl, 1/2 gills)
3/4 oz lime juice (2.5 cl, 3/16 gills)
1/2 oz triple sec (1 cl, 1/8 gills)
2 1/4 oz egg white (2 1/4 oz, 7 cl, 9/16 gills)
1/4 oz sugar (3 dashes)
Add mint sprig
Serve in a cocktail glass (7.0 oz)

I didn't have any fresh mint, so we went without that. It is quite frothy from the egg white (I might have used a bit too much, I'm struggling with measurements for things). She likes it.

Update: Started to separate 5 minutes later. I wonder what I did wrong?