I'm sure the internet could provide you with the answer as to whether or not it's a high dose. As for smoking meth...neurotic is right: that's probably literally the worst thing you could do to yourself. I don't know where you live, but if it's in the US, they love to send people to prison for drugs or drug-induced acts of violence. It's true that you have a psychiatric diagnoses, but it's also largely in your control when it comes to doing meth or not. I would highly suggest that you:
1) stay the hell far away from any stimulant and any hallucinogen
2) take the damned meds until you talk to your doctor at the dose that he/she prescribed
3) talk to the doctor about why you don't want to take it (or why you're reducing it) in a completely honest manner, and don't forget to tell him about your meth cravings; if you want them to help you, you must be as open as is humanly possible
4) discuss with your doctor a possible alternative treatment plan that makes both of you as happy overall as is possible
5) follow the plan that you guys come up with
No one knows if you'll act on the impulse if you smoke meth. We aren't magicians. But whatever you do, even if you decide to forego my neat little plan, know that stimulants are poison for you right now (beyond neurotoxicity, I mean to the extent that if it makes you psycho, your life could literally be ruined).
People who have psychotic disorders and who use hallucinogens make their symptoms worse; that's a no-brainer. People who have psychotic disorders and who use stimulants generally make their symptoms worse - there are reports of people with schizophrenia occasionally being prescribed small amounts of stimulants to deal with negative/cognitive aspect of the disease, but it's not only playing with fire, as the say, but their doses are much much smaller and their method of ingestion much safer (oral) than what your average meth-smoker goes through. I mean a maximum of 60mg amphetamine a day orally, whereas blowing through 100mg of high-purity meth is probably something you did routinely in the past. Keep in mind, too, that meth is at least twice as potent by weight than amphetamine, and that furthermore amphetamine hurts the brain and heart much less than does meth. I'm rambling.
This is the last time (I promise): DON'T DO IT.
