You've only been at a therapeutic dose for 2 weeks. Unfortunately you have to give it more time. The 8 previous weeks on subtherapeutic dose, as far as I know, didn't do much but delay full onset. A lucky few get response at subtherapeutic doses. If you've received any benefit at all, I'd suggest waiting it out at this dose for another month, and increasing again up to 20mg if unsatisfied.