Hey, First of all, ODing wasn't a bad idea because of how and where you decided to do it; it was a bad idea because hurting yourself definitely isn't the way to solve all the things you're dealing with right now. It definitely seems like you've been through a lot in your life so far, but that doesn't mean that the only solution to it is to hurt yourself. You're still young and have plenty to live for.
In terms of your mom, it definitely isn't fair that she disregards your feelings so much. Parents are supposed to be people that you can turn to about these things, and the fact that she is simply writing everything off as attention-seeking shows that she isn't really doing her job. That is by no means your fault. That's her own lack of empathy and responsibility. You shouldn't have to suffer from that. Is your dad still active in your life? If so, you could try going to him about some of this. He may have some better insight as to how to get you some help with this, and how to handle your mom.
If that isn't an option, I would definitely stick with what your counselor is telling you. From what it sounds like, they're putting a lot more effort into getting you help than your mom is. I can understand that you may be worried about your mom's reaction to this, but I think that the important part is that you're getting help for whatever is going on in your life. Is it possible that your mom will credit you talking to a counselor to being attention-seeking? Yes, absolutely. However I think the important thing is that you are getting help. Words can be hurtful, but she can't control your happiness or actions in the long run. Only you have control over that.
The most important thing to remember about all of this is that you shouldn't have to punish yourself for you mom. She is the one who is in the wrong here, not you. The fact of the matter is that hurting yourself isn't going to change her one bit. It's just a permanent solution to a problem that it is fairly temporary. Remember that in a few years, you'll be able to move out and not have to deal with her anymore. You've got a long, promising future ahead of you if you can just hang on and get through all this. It's definitely not easy, but I have faith that you can do it.
Let the people who are trying to help you help. Try to ignore your mom's insensitive remarks as much as you can. It sounds like there are people who are trying to get you on the right track, and those are the people that you can trust and stick with through this.
If you need someone to talk to about anything, feel free to send me a message. I promise I won't attribute any of it to 'just wanting attention.' I really do wish the best for you.
Take care.
-Isobel