I really would like some advice on fixing my situation:

Close to two months ago, I followed my psychiatrist's advice to start taking 40 mg of fluoxetine. I had started feeling extremely anxious, depressed and eventually suicidal, so 20 mg daily after 2 years was obviously just not cutting it anymore. And since my psychiatrist had only advised me to up the dosage as a trial and had not actually written me the prescription, I ended up running out of my medication twice as fast. My parents noticed this & immediately disagreed, first saying that the insurance wouldn't cover this dosage, then that I was following my own advice since I didn't have the doctor's prescription and was just popping pills/self-medicating, BUT, they have finally settled on, "you don't need to be taking 40 mg, its toxic, and what's next, 100mg!?".

Now, even being officially prescribed 40 mg of the fluoxetine and knowing that the insurance WILL cover this, my parents have confiscated and hidden my medication from my cabinet and administer me only 20 mg daily. Isn't hiding my own medication a bit controlling? Should it not be mine and my psychiatrist's decision to have me on 40 mg. They are my putrid feelings that I deal with daily, and now that I know that I genuinely feel better at 40, shouldn't I choose what and how much to take as long as it helps me more than hurts me. Can I really be wrong? P.S: I'm 18+, but covered by their insurance.