I think if all you want to do is express your thoughts in a few words, write a diary or journal.

Poetry is an art form and as such demands artistry. Für Elise or Ophelia by Millais are two very recognisable and poignant pieces of art. They required moments of inspiration (a relationship with 'Elise' and the character Ophelia). They also required an intimate understanding of composition: structure, tempo, pitch, key; colour theory, brush strokes, materials.

There are so many technicalities to poetry and these are the reason poetry has survived as a form of writing alongside prose and drama. Some forms, such as the alba, are very rare; others, like the limerick, can be taught to children. A clerihew is rare but is very similar to a limerick in it's composition. There is a huge range of tastes to acquire and experience and there's a lot of pride to be taken in proper expression. Other people have recommended reading poetry and developing tastes. This is essential. But it won't all come by osmosis: you have to understand what you're actually looking at and why it's enjoyable. Proper expression of yourself must go hand in hand with proper expression in language.

You should read books about poetry. I wouldn't advise poetry about poetry, it tends to be fucking horrific. Stephen Fry wrote a book called The Ode Less Travelled. By his own admission he's not an aficionado but he offers a very compelling and accessible introduction to metre and form. He says:

The point remains: it isn't a burden to learn the difference between acid and alkaline soil or understand how f-stops and exposure times affect your photograph. There's no drudgery or humiliation in discovering how to knit, purl and cast off, snowplough your skis, deglaze a pan, carve a dovetail or tot up your bridge hand according to Acol. Only an embarrassed adolescent or deranged coward thinks jargon and reserved languages are pretentious and that detail and structure are boring. Sensible people are above simpering at references to colour in music, structure in wine or rhythm in architecture. When you learn to sail you are literally shown the ropes and taught that they are called sheets or painters and that knots are hitches and forward is aft and right is starboard. That is not pseudery or exclusivity, it is precision, it is part of initiating the newcomer into the guild. Learning the lingo is the beginning of the right of passage.

I'm saying this because I think there's something implied in "My interest and creative energy in writing prose has all been obliterated by English classes at school." I think it's important not to cower from dissection and analysis. You've been told to experiment. What's the point in experimenting when you have no basis for your hypothesis? What rules are you disproving if you don't even know them?

Fry asks if you'd call a child smashing a piano — calling it 'self-expression', of course — art, because of that misnomer 'self-expression'. You may not like Arthur Schoenberg or Ferneyhough; or Malevich or The Physical Impossibility of Death in the Mind of Someone Living, but these artists always knew the rules that they were breaking before they broke them.

There are issues that remain unresolved in literature. One might be mimesis — how much a representation bears resemblance to a reality. This has attracted people from Plato to Coleridge to Frank Kermode. Then there are the codified basics: metre, form, rhyme, symbolism, phonetics. These must be known.