Awen - I think my little visit to hospital last week is a variation of what you have been having. i think i get really bad braxton hicks when i need to go. and when i need to go i really need to go - not nice, but you are not alone.
I know what you mean. My bowels are just ridiculously lax at the moment and it just isnt pleasant. It is awful at work cos if I need to go I need to go, but if there is someone else in the loo i have to sit there and try to wait for them to leave as I am embarrassed. Have you been to docs? Perhaps it is IBS, not sure if it gets exacerbated in pregnancy but might be worth a shot.