38 weeks + 3 days, have been totally exhausted all day, is this a sign ?

Like most pregnant women I am looking for any sign that labour is near, I am 38 weeks + 3 days with number 3 baby but never gone into natural labour before. I spent the entire day today in bed, the whole day, i was so tired. I have braxton hicks a lot but no show as yet and I haven't lost my mucus plug. I am so ready for this baby to be born, it is just not like me to laze about all day. Can anyone tell me their symptoms in the days/weeks leading up to labour, and how when did you know you were in labour, and how many weeks were you ? Also, I have put on less than a kilo in the last month, some sites say that weight gain slows down at the end ? Thanks in advance.