looking forward to my final exit.

That is all I can think; sooner or later I will end up with my life. I usually have these periods of time where my life seems to be ok, where I feel capable, but that ends up being just an illusion.
I am a 23 year old transgender man. This is in fact the only part of my life that makes me feel proud: the “accomplishments I have gone through to be who I am” Yet, Life is not going well, it never has been.
I will end up with my own life sooner or later that is for sure. There are things in my life where I have just completely fucked up. I have always been a depressed kind of person; I am one those people who has always been alone, kind of quiet, kind of shy. Sometimes I don’t seem to get the world at all, it’s like I have no direction, no way to go. I have been in different places to try to start again but it never works; I have been moving form city to city, but it is the same: I am the problem.
I have dropped out of college two times now because of this problem, I am enrolled again but honestly I don’t see any good outcome out of this. I have reached a point where everything seems far more complicated, I am getting very old, I prefer to end with this, rather than turning into this pathetic looser old man; in fact that seems to be the only fucking image I can have of myself in a near future; a pathetic old depressed failure of a man. I’m loosing everything. I am a parasite to the world and I will do more good if I kill myself. Honestly, I am an idiot and I am not even joking, I am the most stupid retarded person you will ever meet; a person with any mental of physical disabilities has even more strength than I. Seriously, if we are taking about the survival of the fittest , I am the weakest.
I am now considering suicide more seriously than ever before. Yet, I cannot find a 100% method to commit suicide. I am homeless as of right now and I am not sure where exactly I could use the helium hood method. since I am transgender I have access to syringes, yet all the substances that are used as an injection form are very hard to get like cyanide. Any advice on a good final exit method?