Help me figure out what contractions/braxton feel like :)

I am always asked by my OB if I had any contractions but I can never tell because I have no idea what am I supposed to feel when they happen. Ok, I assume when I'll have actual labor contractions, I'll know )) But until then, can anyone describe them?

Doctor tells me "Some women describe them like menstrual cramps" but I am fortunate to never experience pain during menstruation so can't know. Internet says - braxton are painless contractions, labour ones are painful, cool, still don't know how a contraction should feel )

The one thing I think might be it is when my belly gets harder, usually when I lift something or walk fast, kind of feels like the baby stretched in the lower belly and didn't relax. Could that be it? I'd think so but those feelings are mostly triggered by physical activity and don't really happen on they own that much.