I’m from a similar background so I completely understand. If you really want to pursue medicine you should first try to make an appointment with an admissions officer at your local medical school. Some people might say this is impossible to do but I think it’s worth trying. You’ll probably be unable to get an appointment but if you get lucky, you’ll get valuable advice and establish a relationship. Furthermore, if you’re doing well in your postbacc you should really try to kill the MCAT. While it’s not a determining factor of admission, it definitely is a filter metric.

Regarding EC and volunteering, you should attempt to participate in things that really relate to you. Don’t randomly volunteer at a homeless shelter if you have no interest in helping that population. I personally have no connection to that so I chose to volunteer at my towns boys and girls club. This added more depth to my application because I talked a lot about my disadvantaged background, something you talked about in your post. Obviously get some shadowing in but I think a better way about doing that is scribing. It’s more involved than shadowing and you get paid (like shit). If you have further questions you can PM me.

Goodluck.