You are pretty set. I would continue to boost the volunteering; look at some non clinical opportunities as well. Work with the less fortunate, lower SES groups, disabled, in different environments etc is what will really benefit you.
MD/PhD programs are brutally competitive. The median MD/PhD matriculant(note this is a general MD/PhD matriculant not one at a top school) had a 3.8/35. You have a 3.9/36 which is outstanding but there are simply no guarantees with MD/PhD programs. That said, you certainly can be competitive.
Invest in MSAR, then come back with a more specific list. My general guideline to get you started would be yes apply to all Michigan schools(that provides several lower tier "backup" type options), perhaps 6-8 medium tier type schools(think those with 3.7-3.8/34-35 medians like say as one example Rochester---try avoiding schools with significant IS bias like UNC) and then your choice of about a half dozen or so(depends on how many secondaries you're willing to fill out) of the top 20 reach schools of your choice.
The physician scientist forum on here will provide you better input for MD/PhD programs than I can. I would imagine if you are serious about them a good balance of your state programs, some medium tiers and some of the big names is probably a good idea there as well with perhaps it being a better idea to be a bit more conservative for MD/PhD school lists than MD school lists.
. Any recommendations for other schools?
