I'm a little lost on BH..

Can someone explain to me what (in their own experiences) they feel like? I'm a second time mom and well i didn't feel anything with my first at least I think not... when I got to the hospital at 38w2d for my scheduled section my "contractions" according to the nurse were 13 mins apart and syncing with the machine they felt like mild gas/bowel movement pains. But I didn't notice any BH. I'm almost 23w now and I'm still not noticing them... any help would be nice. I'd like to be able to tell when they are happening. Thanks ladies :)