Am I in slow labour?

I am 38+6 pregnant, booked in for a section on Wednesday. the past week and half I have been getting back pains where they do feel like tightenings and are very painful but only come every hour or 2, I have never had these before in my pregnancy! 

My midwife checked me the other day she said baby is back to back. (My last labour was back to back) 

mum having loads of pressure pains which are very uncomfortable and sometimes are stopping me from walking. 

the Past 4 days I have felt very constipated pains coming and going. But not really going to the toilet like my body feels it should.

does this sound like slow labour? Or could constipation do all this?  just don’t feel right at all.