You don't have to be perfect with giving the meds every 12 hours. We tell clients "if you feed them twice a day, give them meds with breakfast and dinner". Sometimes that is 12 hours apart, but some times it isn't. And that's ok.
What meds is she currently on? I wouldn't let the paw licking go TOO long because they can get problems secondary from licking or scratching so much, like skin (staph) infections, yeast infections between their toes, or hot spots... then they lick cause they're irritated... and they're irritated cause they lick... its a vicious cycle.