At the end of the day, this is going to be a big fat no. So - what are your options?
You said you are starting counseling, but you don't think it will do anything for you. You're right - because you're already going in with the mindset/attitude that it won't. Time to change your thinking around. Having an uninvolved third party can be a big help, but you need to want to get something out of it. Consider the therapist as an ally, instead of an enemy. If s/he isn't a good fit? Ask for someone else.
Look at your other options in terms of trusted adults. Is there a teacher you can talk to? A local friend's parent(s)? A coach? A long distance online friend and his/her Mom are one thing, but in-person support is better.
At 15, you're finishing your sophomore year in HS, yes? What are your plans for after? Two years is not long, though it seems so right now. What do you want to do, and what are you doing to get there?
If you're looking at college, you need to buckle down with your academic classes and do the best you can do. Add in extracurriculars. Some added benefits? You can leverage all of those into time outside of the house/away from Mom. Practices, library, study groups, etc. Positive stuff that will beef up any application (actually, this is good even apart from college aspirations - being a well-rounded person makes you more attractive as a potential employee).
If you're looking at a trade, how are you going to get there? Are you looking for summer work in that area? Already have a job? Again, ways to get you out of the house and building your future. Are you doing anything else in your spare time?
I know that it's frustrating to be told you're immature, but..... you're 15. So.... it kind of goes without saying. So if you want adults to take you seriously, you need to take yourself and your future seriously. Present yourself as a young person going somewhere. Take advantage of what is offered to you and work it (i.e. the counselling).