not to go too off topic and drag this thread out, but i will add that i started sharpening my stingers this year before season with the jig\sandpaper method and i have to agree about the difference. I could shave my entire body with these things (weird i know), they are scary sharp...that doe i shot earlier this season legitimately didnt even know she had been shot, she just walked off until she fell over dead, it was incredible. some of that of course is arrow weight, shot placement,etc....i dont even recall hearing the usual thwack sound when i hit her.congrats on finding her! Now you've got some experience under your belt.
I shoot a similar setup to you- 100 gr magnus (ser razors, 4 blade) and around 415 grains or so. I'm shooting 60# and I'm getting about 265 fps (27" draw). I bet you're pushing 280 or maybe more with that long draw length. That's plenty of energy for pass throughs for most shots. The two does I shot last year and the first buck this year didn't pass through, but in all three cases I buried the broadhead in either the far shoulder or in the brisket. In all three cases the deer was dead in < 10 seconds. Two does this year and a buck last year all zipped straight through. A heavier arrow would penetrate better, but these fly so well I'm not going to mess with them.
That's the first thing I would do in your case- paper tune, bare shaft tune, and walkback tune. There's no reason you can't get perfect bullets out of it so if you're not shooting them now you need to get there first. Second, the guys are right above about magnus being sharp but not scary sharp out of the pack. I sharpened last years broadheads before the season. I lost one and chipped one on my 7 pt this year so I ordered another pack. I thought the new ones were plenty sharp until I felt the ones I had touched up. I don't quite go to mirror finish but I do go to 1000 grit paper. I'm absolutely confident it makes a difference.
As for placement, I wouldn't do much differently than you did. Its tougher to tell from a picture and from a deer laying on the ground exactly what happened and what you hit. I always inspect the organs when I take them out to see just what was cut. Based on where that hole is, if the deer was perfectly broadside to you then that's a double lung pass through every day. I'd maybe prefer 2" lower, maybe an inch forward, but we're splitting hairs here. Given the lack of pass through, I suspect that there is a combination of poor arrow flight and/or the deer partially quartering away. You're high enough that quartering away would hit the scapula on the way out and could stop the arrow. if the deer is more broadside but the arrow hit at an angle it would push up into the scapula area too. Its still a lung/double lung but high and forward on the lungs has less blood vessels. You might have only caught a single lung also and the lack of tracking blood would have helped you in that case- you gave up which gave the deer time to go lay down and die instead of running forever. We'll never know for sure, but I wouldn't worry about where you stuck the arrow in her.