Problems breaking lower guitar strings on electric?

I have a Schecter C-1 Diamond Series guitar. I've owned it for about a year or so and I keep breakins just on top of the bridge. The most common strings that keep snapping are the low E and A strings. I've recently tuned mostly to Drop C and play a lot of palm muting and and 16th notes. I regularly bend the higher strings a lot (not usually lower) and use Ernie Ball nickle slinky regular .10s or hybrid .09s. I have been playing for about 9 years and break a string sometimes ranging from once a week to once a month. Anyone have any ideas for me? I tend to play a lot of metal so should I try heavier gauge strings or maybe replace the bridge? I play using thin picks.