I don't know about the hormone stuff, but I wouldn't worry about the toddler jumping on your belly. My DD has treated my pregnant belly as her personal trampoline for some time now, and the baby kicks along in response.

its hard, but now is the time to trust in the process and believe everything will work out ok. Its a hard process, but so important for all us parents...because now you have a great big unknown nestled inside you...another life...and we really cannot control what they decide to do.

I hope you get some ansers soon.