Suggest that you:
1. Eat more weeties for breaky ;) ;D
2.Get bigger baskets than the standard Silvia ones if you have not already done so...
3. Dose up- prehaps try a few bench taps before levelling off and tamping
4. Aim for about 25ml in a 25 second pour and yes- you do want to see a dry puch with no channels. Cut the shot short if you see blonding.
5. If the espresso is sour (tip of tongue) or bitter (rear of palate) try making the grind a little finer or coarser respectively...