Living in the Woods of VA many accidents with deer and bikes- these things are very true with deer
1. They Never travel alone (if you see one others will follow)
2. Sounding Horns (Startle them and they will bound out at you)
3. Headlights make them freeze (when They see it) (that's called Spotlighting) Hunting term.
4. If the Deer where SPOOKED and running at full speed none of the above apply-I think that what happened in your case.
Deer will Run wildly During Rut Season, Or Hunting season (Most rural county's in VA allow Dog use Hunting for Deer)
A major pain in the fall around here as they will Run fast and hard. (Deer Whistles DO NOT work) or (Work as well as the little bell so folks tie on there bikes) It a Belief system.
Depending on how fast you where going if you had slowed for the first chances are the second or third would have knocked you down. SO as with most motorcycle accidents the rider will never see it coming.
You are very luck one of my friends is still in ICU and his accident was 4 weeks ago.
I'm sure you bike had loud pipes so a horn would have been a mute point-

When I was a Boy in this area Dear were few and far between- (NO Stores) or that many people deer were hunted for food!! AS this place grew and more folks and stores moved in they have over bred everywhere and now that most must love them (Bambi) It gotten even worse - in my neck of the woods I kill'em cut the tenderloin out and throw the rest on a gut pile (year round) but alas I can't do it all.
I know you must be feeling better because you are typing along with us - Good Luck on your recovery.