Just on the face of things....
You say you're feeling overwhelmed by your life situation. You feel isolated from home, have a baby, have an impending wedding, and all that. From my point of view, that's not a good time to toss in additional major changes--which are sources of stress--to your situation. When one considers that your response to being stressed initially was less-than-healthy, adding more stress to your situation becomes less appealing.
I'll recommend slowing down. Figure out how to handle the stress you have and deal with those issues prior to adding the demands of new relationships. It'll also give you some time to wrap your head around what engaging in multiple relationships is likely to be like and how it will affect your lives.
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.