I had no success with traditional speech therapy as a kid and in my teens. I've found online coaching (which has a bad reputation here, so I won't mention the company name or the author) and had tremendous success with it, spending maybe 500-600 USD on it in the last year (I'm not perfectly fluent yet, but speak much more fluently and also have more confidence). So, I'd recommend to find a method that suits you, don't spend money on it initially (if you can do this) and don't let yourself be fooled by unproven claims.