I Am A 46 Year Old Female- Been Having Night

i am a 46 year old female- been having night sweats since my 30's= I was due to get my period 12/7/14- and still have not gotten it- I am underweight to begin with - but I have lost a couple pounds- (now 101- and I am 5'9) I work out and eat the same things every day- (although I have been trying to eat more- although not readily gaining) I feel fine- but I cannot afford to loose any more- could this be related to early menopause