You have been through a lot in your life and right now you're in a place where you can't see anything better, but trust me, things can get better, suicide is NOT the answer. Most of the things listed above are things things that you cannot change, so what to do now to get out of your rut is to focus on the things you CAN change:
1. Even if you are truly "not very smart" (not just self-deprecating and saying you're not smart because you're feeling bad about everything right now) not smart people still graduate from high school all the time! Definitely keep showing up and doing your work, just do what you need to do to graduate!
2. Once you graduate, you could apply for the military/one of the forces and they will pay for your schooling. This is one option.
3. Do like a lot of people do and take out student loans to go to college. I came from a family without much money and that's what I did, haven't looked back. This is your life you're talking about.
4. Try online dating. See if you can meet people that way since you're not having much luck at school. At least browse to see who's on there, consider making a profile.
5. Find a counselor or some adult you can connect with. I know you mentioned the current counseling is not helping, but keep searching for an adult who can serve as a mentor for you since your parents are unavailable to you. If you've been going to the same counselor for awhile, pick a different one. Sometimes the same one doesn't work for everyone.
6. Explore your spiritual side. Just because you don't believe in God, does it mean you also don't believe in soul? In emotion? In energy? Read about different concepts online and ask yourself tough questions about how you think creation happened, challenge yourself to think beyond what other people come up with. Think of what you can come up with, make it your own. It is your own personal belief.
7. If you're feeling really unstable and think you might harm yourself, seriously call your local hospital and let them know you think you need a psychaitric evaluation. They can help stabilize you and set you up with resources to work through some of these issues and get your life back on track.
8. Challenge yourself to change your perspective. Has everything you've been through been things that have brought you down, or have these things served to make you a stronger person and the person you are today. Imagine yourself in different scenarios and how you would respond - lost in an unknown city, dropped in the jungle, etc. I bet with your life experiences you would fair much better than people who haven't been through the things you have. It doesn't make those things better, but it shows how strong it's made you.