Waters breaking/leaking

TMI - Just wondering how you know if your waters are leaking if it's a small amount at a time? Yesterday evening, my underwear was very wet when I went to the toilet, but no smell of urine or discharge. I changed my underwear and an hour later there wasn't anything in that pair, but I was "wet" in a way - but not from arousal or anything - there was no smell again, so I decided to leave it overnight and see if anything pooled in the bed or my underwear - it didn't. This afternoon it kept feeling like there was excess fluid down there (I was in the cinema though so couldn't properly check!) and now that I'm home I've checked my underwear it's damp to the touch, but no visible wetness like last night, and not as bad, but no smell still. Could this be a very slow leak of waters? Or anyone else have any experiences as to what it could be? I am 38 weeks amd 3 days. Thanks in advance!