Is my body preparing to labor soon?

So I'm 35 weeks today but this week I've been having extreme pelvic pressure which was reassured with what was supposed to be my last ultrasound yesterday, she's 6lbs, head down and I've dropped.However she's measuring big so they rescheduled me for a 38 week scan for a final fetal weight measurement. Well today I've had the extremee urge to poop all day but when I go to the restroom either it's lil rabbit poops or diarrhea but the pressure is unbearable. All week I've had braxton Hicks at least once a day. Friday I'm having my cervix checked in just worried I'm about to go into labor I can't shake this feeling!!??