I just wanted to add that the stabbing cervix pain can be caused by the baby's head rubbing down there. I think it was someone on here who I initially learned it from, but I asked my doc's resident, and he said that it is quite likely.
Also, I don't remember any back pain whatsoever with my first labor - it was all in front and I only really recognized the contractions since they followed a pattern (coming on, going completely, then coming back again, in waves), until I was close to pushing and yes, it did feel like needing to poo! Nice imagery, huh?
To tell you the truth labor feels like you have to poo very bad... i know that sounds very nasty i thought so too but it does mixed with period cramps.
I was 3 weeks early. My early labor contractions I would describe as "little fires" only in the front for me and they had a burning sensation. Later, in active labor, it was all the way around to my back and undeniably contractions. It is different for every woman and that is why there is no definitive answer. But, you will know. The early labor stuff can be confusing. My midwife gave me a good tip...if you think you are having contractions but aren't sure...draw a bath and get in it. Drink a big glass of water too. If your contractions speed up, then it is labor. If they slow down, then it's false labor or early labor. Good luck!
I was trying to sleep, was uncomfortable not thinking I was going into labour. My tummy and back were acheing. So the answer to your question is your back and stomach will tighten. Its very much like very very bad period pain. Are you planing to have epidural our drugs? I had gas and pethadine. 7 hours and he was here, 3 days early. Plus before I went into labour I had bacon and eggs plus 3 fish oil tabs. 3 hours later I was in labour. Good luck not long now.
Contractions feel like REALLY intense menstrual cramps...its not the cervix pain your feeling...that may just be your cervix thinning out...contractions are totally different... :) your close...good luck!!