Before we decide on any form of therapy, ever, we need a good diagnosis --- until we know exactly what it is we want to fix, we can't know how best to fix it. That's what's always wrong with the various pop therapies and remedies, which start with what they want to sell you, and work backwards.
What you most need, from the sound of it, would be to re-visit your prescribing shrink, for a re-assessment of these new features, and a reconsideration of treatment. A wide range of medications can make it more difficult to concentrate and, hence, to remember things ; and a number of meds can cause some disturbance of our articulation and speech --- and if that might be the cause, it would make more sense to vary the medications --- a speech therapist might not be able to help in such cases, as the problem would be beyond their control but probably easily relieved by variation of drug type or dosage
I notice your cocktail is of recent and rather expensive meds --- perhaps logical if older and cheaper meds have already proven ineffective in your specific Bipolar disorder. Clueless has an important point, and Topamax can make one feel dulled and slurred or the difficulty mentioned in finding the right word.