With BH I felt my tummy go hard too and it would quite often feel uncomfortable, and then it would go away.

With the sharp pains - I got them too - and they were very stabby-like. I was getting them for several weeks before Jacob was born, but they'd stop me in my tracks wherever I was (quite funny being at the supermarket and people thinking I was going into labour when I wasn't - I just had a sharp cervix pain LOL!)

With the proper contractions, I found myself wanting to do things like stand in a certain spot or rock or something like that to get comfortable and they were definitely period-like as well as being in my back. At the time I was unsure as to what was happening, although being overdue I thought something was going on! I had a bath and a couple of panadol and they kept going, so it was all happening alright!

Good luck!