Real contractions? Help! FTM

I'm 34 weeks with twins and have been having contractions on and off for the last few weeks. Last night I lost my mucous plug. Or what I assume to be my plug. It was huge greenish ball of phlegm and it was nasty!! I woke up this morning with REALLY bad cramping. I knew they were contractions, but they didn't feel like the usually tightening, it's just bad cramps. When I lay down it feels better, but every time I go to stand it comes back and hurts again. I've heard with BH they get better changing positions, but are they really getting better since they come back as soon as I stand up again? I feel bad going to the hospital again because I've gone countless times and nothing has changed. Does it sound like real contractions, or am I looking at more BH? I know that the only REAL way to tell is by going to the doctor so please don't comment with that. If they start to hurt so bad I cannot talk or breathe, or my water breaks, j will surely go. I just don't want to waste my time.