re: I cannot hold a train of thought.
Yeah, I have this same problem. This is one of the reasons I rarely post. A lot of times I'll intend on posting something or replying to a PM or whatever, but end up putting it off for weeks at a time, in some cases just dropping it completely. I find the whole process to be very mentally draining with little pay off.
Also, I think because of how unnatural it feels for me to express myself in this way, I'm unable to write things starting in sequential order; instead, I'll start with whatever is on my mind, and worry about making it sound remotely coherent afterward. And I'm sure this is probably noticeable in my posts, too (which is all the more reason not to post).