I am 29 weeks pregnant and fell very uncomfortable..?

i am 29 weeks along..and i beeing feeling all this..if i am moping or walking alot my back waist hurts like if is kind of broken..and if i am sitting on the sofa all the way to my back i star to fell a little bump on my stomach i dont know if this is my baby butt..and then i start to fell some pressure on my pelvis..and can fell my uterus tigh..and i also fell little pains on my lower abdomen sides..does this means i might go to labor sooner or this are braxton hicks?? my due date is on sep.07....and i got 2 kids allready this is going to b my 3rd..