Your elbows should always be bent. If that leads to back issues, well hey! There's a solid data point. Your bars are too far away unless you can learn to relax and bend/stretch further forward. Unbent elbows lead to road shock, rude surprises when you hit things you didn't see and chronic-like injuries. Bent elbows are your G** given shock absorbers.

Based on your report of issues with your left arm, that is the first thing I would look at (in part because it is easy to see and address).