Feel free to ignore my advice since I'm just an angsty Athiest and stuff but honestly why don't you just go for it? Teaching sucks, ditch that shit. Simple as that. Maybe you'll discover Marine Biology sucks also, or maybe it'll be the greatest thing since sliced bread. Maybe you just need to go to another school, try to find a job in a small town school where you can bond with the students better. 

Seriously, what's stopping you from following your dreams? Money? That just means your going to have to work your ass off outside classes to pay for them/learn to love ramen. Parent disapproval? Is it your parent's life or your life? If you hate the way teaching is going for you and you cry every night, obviously their approval isn't doing much anyways. The amount of effort it'll take? If having a fulfilling life was easy, everybody would be doing it. There is a reason Thomas Jefferson said the 'pursuit of happiness'. You're waiting for God to step in and magically show you how to live happily ever after? Well you're going to be waiting for a long time I guess while others take chances and, I dunno, actually live life? If your unhappy with your life, don't wait for God, just do it yourself. Maybe at the end if the road you'll go back to teaching, shit who knows what can happen. But the way it sounds is that your not exactly living it up right now so why not make a few dumb decisions?

That's just my two cents. I just hate when people rely so much on others/God/etc. to pick them up when their life is shambles. If you have two perfectly good legs to stand on, walk. Don't just waste away slowly in hopes that somebody/something is gonna come by and carry you.