Guys, guys, please: Let's not forget what the topic at hand is, and if someone is coming here honestly and wholehartedly considering CTB, then this person must be utterly broken to take such decision. Please, don't be harsh with her, consider her situation, most of you probably share a similar situation. She has never received enough support on her life to make it worth living, let's at least give her some support on her last steps before ending it.
No medication is necessary other than the SN. Other medications are meant to lessen the symptoms, symptoms that are not painful and only cause disconfort if you don't mentally prepare yourself to feel them, as SN will take up to half an hour to finally kill you, and it may be scary to feel such symptoms if you hadn't contemplated them beforehand: dizziness, feeling very tired, loosing consiousness, a slight tachycardia, some slight headaches, and a very important symptom, vomits. The other symptoms, are ones that you should have no discomfort with if you mentally prepare for, and if you are absolutely certain of your decision, not letting that last half an hour of your existence to be a moment for you to reconsider this decision. Now, vomit: your body will try to expel the toxin you just pushed into it, and vomits is its way. The best solution, is fastening, for 8 hours with only water, and even little water. This will ensure your stomach will have nothing to puke with, and make the absortion of SN be faster, so even if you puke, by the time you puke, it'll be too late, your metabolism will have already consumed the SN and it's effects will give you the peaceful end you deserve.
So, what I ask of you, is first and foremost: Ensure this is the decision you want to make. That there is no point in continuing with this life.
I do hope you take this time to truly think of this decision, to ensure there are no reasons for you to keep living. Life may be complicated, and never filled with enough happiness for our souls to shine as much as we wished to, but it is the only chance we have on this material world to make something unique, that may rise ourselves or others. If you truly think there is nothing else for you to do on this earth... then I support your decision, and know you'll find peace on the afterlife. We may meet there, shall you leave us soon or stay with us for a bit longer.
Best of luck, friend.