guinnesschick,D'Addario also make a slightly heavier set (they might still call it the "Grisman" set) which starts at .011 and has a slightly heavier gauging right up the set (up to 0.40 if my failing memory serves). These might overcome the problems you're encountering. Some other string makers may also offer a heavier grade.
I have changed from the normal D'Addario .010-.034 set to Elixirs on my mandolin and have been very happy with them. I also use Elixirs on my main fingerpicking guitar but still keep to D'Addarios on my plectrum-powered chord backing guitar as they seem to suit the sound better on that.
mooman
mooman