By the way, really steep angle shots are not good for bowhunters.
The spine and shoulder protect too much of the vitals. There isn't an arrow made that will consistenty defeat a deer's shoulder, and a solid hit to the spine will stop even a heavy arrow dead in it's tracks.

Next time either catch him broadside or quartering away as he is leaving.

Sorry to hear about the so far unrecovered deer. I hope you nailed a lung good enough that he'll drop soon enough to be found.