I really liked the reading of this poem so I wanted to take a shot. This is a partial answer.

I believe the subject is 

>! Some form of the birth/death/time cycle

Though a different shape, my form I take
From that which bends but does not break.

>! LIGHT bends but does not break, and in this case, the form is SUNLIGHT

Two in love, or simply lust,
Doing as they feel they must.

>! MATING is the obvious choice here

The rhythm of a heart that beats,
The changing patterns of one's feet.

>! DANCING 

A helping hand, a bandaged knee,
A slow but sure recovery.

>! FALL, which is also a season

No clouds in sight, a gorgeous day!
A flower always bright and gay.

>! This describes a typical SUMMER day

From trees that never lose their leaves
To dusty pollen on the breeze.

>! WINTER has evergreen trees

I weave a spell with just my words
Hoping that I may be heard.

>! This seems a bit forced, but ROBINS are said to announce spring

The sound of water's like a balm,
A flowing sense of peace and calm.

>! And this describes a SPRING

What makes you, you? What makes me, me?
The thing we are, but cannot see.

>! No clue

I have changed throughout the years.
I have seen my share of tears.
But I still shine on, you see,
Tell me now, who might I be?

>! The SUN shines on... but I'm not convinced this is the answer even though it is a bookend with the first clue.  

So finally

>! The clues all seem to involve birth, life, change, and time passing, but I am unable to link them.