Contractions

This may be truly unrealistic, but does everyone for sure know what a contraction feels like when it happens? I'm 32 weeks and I haven't had any Braxton Hicks yet (that I know of). I tolerate pain extremely well (broke my foot and tore all the ligaments and it took me 3 days to make it to the doctor, Just one example of my pain tolerance). Im just worried I won't know when I go into labor - is this even possible or am I being unrealistic?