The sharp niggles, are they painful or just uncomfortable?
As for waters breaking, with Nina it felt like a pop and water gushing out. Mine didn't trickle, it gushed LOL. With Emily, I was well and truly in labour and when my waters broke I felt like she was going to fall out.
Hopefully it's braxton hicks, but it may be more. Considering things could happen any day now for you.