plus sized and contractions

Have any plus sized moms ever had trouble with the monitor picking up contractions? I know I'm having them and they are painful but the monitor isn't picking them up at all. The nurse is treating me like I'm lying or something. She also says my belly isn't really hard during them... I'm over 300 pounds, my belly has felt soft my entire pregnancy. I'm 40 weeks. This is very annoying. She's refusing to check my cervix.