problems when clipping nails

Question
I have an 8 year-old female pug (spayed); weighs 18-19 lbs; eats Science Diet ZD Ultra- Allergen (skin allergies)
After clipping her nails too close (3 yrs ago) I have taking her to the vets for nail clippings. She becomes so stressed: trembling in the waiting area, then yelping, snapping and struggling. Several holding techniques have been tried, the vet suggested Composure (a calming supplement) given daily and using 3-4 pieces right before coming in for a nail clipping. I have tried this twice and am not impressed with the results.Before that I tried Benydryl before-hand.

Is there something else to try? She has become infamous at the vet office and  known as the drama queen of all time!Her nails are now longer than they should be. I don't know wether to wait as long as possible between clippings (2 months?) or try a more frequent schedule in hopes of desensitizing her to the procedure. Thanks!

Answer
Pug anxiety give Valerian:
Oh, poor little pug kid!
Give her a time release Valerian the night before and the day of the nail clipping event.
SEE here:

http://en.allexperts.com/q/Golden-Retrievers-2532/2009/8/Anxiety-golden-retreive...