Structure for a Non-Structured Person

Snowflakes were flying yesterday morning when I got to school. Snow in April?! Right before spring break?? It didn't even snow during winter break! Weather can be bizarre...
Anyway, I have a lot to accomplish during spring break, but at least I can relax! But for me, relaxing always comes with pondering. Lately, I've been considering: why do I, as a writer, have trouble with structure? This question has come up a lot in English class lately, where I've struggled a bit in perfecting my papers. This year, I've had to utilize textual support extensively into my papers as well as master focused writing. Both of these aspects are challenging to incorporate effectively but are an inherent part of structured writing.
One reason I'm not good with structure: a simple lack of consistent instruction. Now, I'm not criticizing my teachers at all: I've had many good teachers and hope to have more in the future. The problem is these teachers all have differing methods of teaching writing. What you learn one year may not apply the next year. So when it comes to structured writing, I've basically had to adapt to each teacher's method and then start from scratch again. I never know what is right and where to start. Additionally, I've picked up most of the basics in my own ways, which is why I usually end up doing my own thing when I write.
In turn, another reason I tend to stray from rigid structure is because I'm just not a very structured writer. My blog posts are a very lucid example of this fact. Even when I'm actually paying close attention to the fine details while writing, I seem to lack any particular structure, apart from the format for 5-paragraph essays. I write, write, write until I've emptied my disillusioned brain of all my circumventing thoughts, made my point, and feel satisfied (which is never). Then, I go back to make sure everything is connected smoothly and transitioned effectively, my examples match my point, and I have proper conventions, mechanics, semantics, etc. It usually suffices, since my work ethic allows me to finish with an decent paper at the very least. For the most part, I manage to use some semblance of structure, so it's not like my thoughts are completely disorganized. Disorganized writing is a pet peeve of mine.
However I choose to write something, my limited structure makes it difficult to sum up my thoughts accurately, especially when I have a lot I wish to convey. My mentality as a writer is to create originality, not rehash, so I find it hard to implement rigid structure. This is especially true in creating focus, where it is suggested that the writer repeat the same phrases for emphasis. It goes against my style, but focus is crucial to any piece of writing.
I'm making it a goal to practice more structured writing not only because I will need it very soon for AP English and SATs but also for my own good, I suppose. Practice makes perfect...I guess. Hopefully, the non-structured me will become more structured. Only to a point, though: while I think no structure feels empty, too much structure irks my creative freedoms and drives me insane. Perhaps I should aim for half-structured? ;]