I dont think your chain is too short.I think its just because your in those gears.You shouldnt have chain on both largest gears at the same time.If u look at from the top down at chain it should remain as straight as possible. I know for sure that now ur running at a pretty drastic angle for a chain.This puts too much stress on the chain.
Yes if it was longer this wouldnt be a problem, but if was then you may run into problems in other gears being too long.This is just my guess.Trial and error,take to a shop and see what they think.
Sometimes this sint a problem but often times it becomes one.