The key to getting a job (at 17 and for the rest of your life) is networking. Volunteer, go to Meet Ups -- do whatever puts you in touch with people. Those people will always be your source of job opportunities that you would never otherwise know existed.
This is why even poor people who go to Harvard wind up rich and people who go to community college wind up in the same economic class as their parents.
It's also possible that you're not making the right impression. I hired high school and college students in retail for years before moving on. The best book on getting hired is this one.
And finally, here's what most young people don't understand: Nobody gives a shit whether or why you need a job. When you meet a manager for an interview, they have exactly one question: How will this person make money for me? So many people I interviewed would give me their hardship story -- I didn't give a shit. I heard it ten times a day. All I wanted to know was whether this person would a) effectively connect with customers and other staff, b) not steal from me, and c) be able to be trained to do whatever I needed them to do.
Be professional. Speak well. Dress appropriately. Play the game. I never cared about tattoos and crazy hair, but if you can't speak like a moderately professional person for 30 minutes (not mumbling, not swearing, not using words you don't understand), then you're not getting hired even to flip burgers.