I like the ending, but not the beginning. A simple list of the months of the year are not very poetic. I think it would work better if the months were interspersed with the other thoughts rather than a simple list at the beginning of the poem. As is it, it just feels like they were added to make it longer.

Yah, I’m with JP. I get what you were trying to do here, but it just didn’t really work.

Interesting concept, but you need something to accompany the listing of months – I agree with JP.

Also, with the last sentences, maybe you should use “i”, so its a real shocker at the end when you introduce a “you”. Example:

All these months I was happy
… I was with you
… I was in love
And then: Only you weren’t