A nice opening stanza, needs to be sustained though. When you have something like this, where you've started and are unsure on how to go any further you need to make sure you don't lose your theme and message in the mix of the imagery you're trying to create. It continue with an extended noose metaphor of asphyxiation or similar. As though your "secret doubt" was constricting you, making things hard and being in the true fashion of the confessional poem, you should always include some emotion. Good luck and thank you (: