Yep I have had these period pains too; and like yourself I'm not sure if they are BH because I have never really felt the tightening sensation either.

For me the period pains get stronger as the pregnancy nears its end, to the point that they wake me up at night and I think - Oh I'm going into labour - no I'm not - yes I am - no I'm not. Frustrating!

I also get them if I'm sitting in one position for too long; sometimes at the computer or driving.