Wow people, really? Grow up.
OP, I think qualifying for federal assistance gives you the ability to claim disadvantaged on your application,
https://services.aamc.org/AMCAS2_2009/WebApp/Help/WebHelp/Disadvantaged_Status.htm
I was under the impression it was based off your family, birth-18 years but I guess it changes when you have a family of your own. Im not sure how accurate this is, or who I heard it from, but disadvantaged status was put in place because not every applicant can afford an expensive private school, mcat prep course, tutors, some have to work so they don't have as much time for ECs. For those who are going to jump down my throat for saying that, I'll add that I don't believe this holds much weight either way.
I was in a similar situation as yours from 16-18 (minus the fed aid thing) and filed as a disadvantaged applicant. Many secondaries have "overcoming obstacles" essays, and for you this is a great place to talk about continuing your education with a child regardless of the sacrifices (financially) you'll have to make. If you do not claim disadvantaged and choose to write about these things, there may be a disconnect. On the other hand, some people will tell you not to talk about it at all because it will be viewed negatively.
Long story short, best thing you can do is 1) contact schools you'd like to apply to and get their opinion on the disadvantaged status and 2) find someone knowledgeable and with good intentions who can help you along the way (premed advisor would be a good place to start)
Good Luck
🙂