First, a disclaimer: my intent is to encourage and (hopefully) help. None of my comments are meant to be discouraging or disparaging in any way.
That having been stated, I'm sure you are sitting back waiting for me to be an a***ole with this review. Well...I'm going to be honest, and I'm going to offer suggestions to the point of seeming intrusive, possibly.
Why? Because this is a strong piece, personal, and important.
But since it is personal, certain changes or suggestions may not be welcome. If not, just close this review and forget about it. If you're still interested in my (arrogant?) opinions, read on!
Okay, first thing I want to talk about is structure. Two points:
Repetition: you have some great instances of repetition in here: "I wait for you...", "I sit and wait...", "I sit..." Also, the repetition of "...not" as the end of a line. In poetry, repetition like this helps the reader reinforce the current stanza or strophe with what he or she has read earlier in the poem. "Oh yeah, he said he 'sits and waits' in the first two stanzas also; his writing right now must reflect a sense of frustration or expectation.' However, the repetition doesn't carry through the whole poem--kind of like a great guitar riff that disappears halfway through the song. My suggestion is that carrying the repetition of these patterns throughout the poem--maybe as the beginning of the first line of each stanza, and the end of the last line, respectively--would give the piece a momentum and rhythm that is missing. In fact, if one reaches a little further, if the end of the poem resolves something like (and this is me being intrusive) "I sit and wait for you/With a smile on my heart/...[some other lines].../I love you, I do./And I always will,/So I will sit here and wait for you.../And I will worry...not." would use the repetition as a contrast to its previous meanings. This contrast closes the circle and helps define the resolution. A lot of poets use this reversal of meaning, and I think you could use this tool to strengthen this poem, as well.
Basic structure. Erm...there really is none. And that is not to say that there needs to be. However, I will offer that this poem tends to wander, and that some structure might help it stay a bit more focused. One suggestion would be to pick a form--say, make your verses 8 lines each, with a rhyme scheme of AABAABCC. That's a random example, not a specific suggestion for structure, but I hope you see what I mean. Now, once you have that structure defined, rewrite each one of your stanzas into that structure. This enables you--forces you, really--to omit all the unnecessary articles, adjectives, etc. that make some of your lines too long, some of your line breaks awkward, some of your sentences stilted. OUCH! That comment might have hurt a little; sorry. But the bottom line is: edit and prune this beautiful wild rose bush of a poem into an elegant bouquet.
Those are the main points, but there's a couple others I want to make real quick.
Most of this is written in the passive voice. Simply stated, it sounds like Yoda wrote it. I would suggest a more active voice. For instance: "then inside my head it begins to pummels" could be stated actively as "it pounds inside my head." It not only reads more smoothly, but it gives the topic passion, gives it momentum, gives it immediacy.
You have some tense-agreement issues. Especially in the fourth stanza, where a strange past-perfect tense crops up. Again, poetry written in the present tense--especially emotional poetry--has some of the strongest impact because of its immediacy. The reader is able to put herself in the writer's mind right now.
Word choice. Just a couple instances of this. "The worse days of my life..." in stanza four should be "the worst days..." Also, in stanza two, "holy cow" is totally out-of-character with the rest of the poem. Perhaps "cry your frustration at me" or "at my heart" or something like that.
So what do I like about the poem? Everything else! We have all been friend-zoned. But not all of us have been able to navigate the transition and maintain the relationship, especially as strongly as you have done. The message is personal, but has strong inspiration for the readers as well. So I think it is an important piece, and definitely worth taking a second look at.
Again, David, these are all just one reader's opinions. Take the ones that you find helpful (if there are any) and apply them as you see fit. All of the preceding is intended as support and encouragement, and nothing else.
Best wishes on your writing!