just a little confused twins gestation

Hi everyone so I'm a few days off 34 weeks Iv had to change doctors due to mine going on holiday 
My last doctor told me that I was coincided full term at 38w this doctor said 36w
And my last pregnancy not twins is 40w
So what's correct? 
And when is the earliest it's safe to have my bubs I'm scared of early labour doctor said he didn't think I would make it this far due to my history and the fact Iv been at 2cms for a week 
I'm rely confused by the whole when is full term as this doctor wants to induce me at 36 if I make it my last doctor said 38w