BH contractions

I'm 36w5d. Every time I see my doctor, he asks if I've been having any BH contractions. He explained everything about them to me and how they differ from real labor contractions but to my knowledge, I haven't been having any. At times, I will feel my stomach tighten but when I hold my hands on my stomach, it's just baby moving positions and the tightening feeling never happens consistently plus I never have any pain. Is it possible that I really haven't been having any although I'm this far along or am I somehow missing them??