how soon will i go into labor? FTM

i'm 37 weeks today and a couple weeks ago i went to the ER and they said i was fingertip open but it wasn't labor. this past thursday i went to my dr apt and she checked my cervix and said he was low (did she feel his head?) and it was thinning but i'm not dilated and she said i won't make it to my due date (march 25th) i'm guessing because i'm really small (4 ft 11, 125 lbs) and hopes i make it another week. 

lately i've been having trouble simply walking because i feel like i'm being stabbed in my groin area (i know it's normal) but it's to the point i want to cry or don't want to move out of bed.. and i've had extremely bad bh contractions and thought twice for a few minutes it was time but they went away. and i just feel like i'm getting my period also i've discharged a lot and can't tell if it's my mucus plug i attached a picture i know GROSS but it's yellow and my underwear is a little wet sometimes also i've been having to poop more (sorry tmi). am i close? or just part of the end of the last month? how will i really know it's time other then "you'll know"? i've come so close to telling DH just take me to the hospital cause my body hurts so much. i'm a FTM so any advice is greatly appreciated! i'm sorry this is so long!