If you have never had a history of drug abuse problems than I may be inclined to agree that for some people medical marijuana could be a good medicine for bipolar.
As far as reducing your meds, it would be wise to just talk to your dr or pharmacist about it.
You said that you feel amazing and my only concern is that we are not supposed to feel amazing. Happy-yes, sad sometimes, but amazing can go away and the opposite of amazing is not sad it is miserable.
Oh and don't take them together, leave at least 24 hours from your last dose of Sertraline before you take your first dose of 5-HTP. If your withdrawals from the Aripiprazole cause you problems add in 900mg St Johns Wart 2x daily and this should help with the symptoms.
Note: 25mg 3x daily should not induce mania, but with the oral equivalent dose to the patch mania is common.
Ditch the idea of Marijuana if you want to live a normal life. I would try replacing the Aripiprazole (Abilify) and the Sertraline (Zoloft) by taking 25mg of 5-HTP 3x Daily for 1 week as anymore than this could induce Serotonin Syndrome. I would then recommend swapping the tablets out for a 5-HTP transdermal patch which will release a more even dose of 5-HTP throughout the day especially if you have BPD as otherwise the oral form could cause mania.