1) Make sure you are competent. Unfortunately, autistic people get judged a bit more harshly, not only due to things like missing social cues but also due to things like flat or unusual affect and speech inflections. People can and do overcome this hurdle; however, if you want something that isn't FM, IM, path, or possibly EM you're going to want to be in the top half of your class or at least have scores in the top half. It's hard, but you'll want to be a bit better than your classmates and know your stuff in order to compensate for whatever bias - warranted or not - that you're likely to get. Subjective evaluations are a big part of your grades in medical school. It's not going to be terrible, most likely - you're going to graduate and have a job at the end of four years if you do your part. It just might mean that if you want something competitive, you're facing an uphill battle.
2) Work on
anything that can be articulated, after you've got the academic stuff out of the way. You're consistently in the top half or at least very close to it on your pre-clinical tests (which lay the foundation for your shelf exams and Steps). You now need to work on building rapport and engaging with patients. There are some simple tools you can use for that: get on their level, don't stand over your patients. Use a clipboard to write things down if you need it. When you make eye contact, use it as punctuation or to get their attention. Same with tone of voice and inflection. You might have an autistic "accent", where your affect is flat and you start and stop words abruptly. Listen to how celebrities, politicians, and podcasters talk, and imitate them.
3) You're going to have to do some soul-searching here. The specialties you
can get may not be the
best fit for you. If you don't fail anything, aren't terrible in the interview, and are a US MD you have an excellent shot at FM, IM, or EM, autism or no. However: is that really the best fit for you? How good will you be at building patient rapport if you miss social cues? These things
aren't so large that they'll mean you can't be a good FM doc; after all, you got past the medical school interview. And again - there are ways to compensate for this, although they're not perfect.
For now: If you have the money/insurance, see if you can see a speech pathologist that works with autistic people, preferably low-support-needs adults. If not, I'd suggest videotaping yourself and listening to yourself talk; odds are even if you're awkward as hell yourself, you can tell when others are awkward and thus if you yourself are doing a good job or not. Also improv/acting classes, maybe get a job as a barista if you can.
Good luck with everything.
Finally: if you aren't already, consider seeing a therapist; medical school is not easy and as
@Goro says, can be taxing for even healthy people. I wonder what MDs like
@IlDestriero or
@NotAProgDirector think as well as adcoms like
@LizzyM and
@Moko. They've got to have let you in for
some reason...
P.S: If you want something like Derm or ENT that's nosebleed-competitive...I hate to deliver bad news so early, but you're climbing a huge mountain with extra rocks in your backpack. You're going to want to seriously consider backup specialties if you're going for that. FM, IM, Path, and EM should all be very realistic for you, however.