Why am i losing weight?


Ok so recently ive noticed that ive been losing weight. Let me give u some back story. Ok so maybe about 2 years ago i used to weigh 140lbs (im 5ft) i was considered overweight. So i decided to lose weight. After some months i got down to my goal weight 115lbs. I decided to stop my dieting and lessens my workouts. I wanted to maintain my weight i was happy were i was. So then throughout the year i was noticing that i was still losing weight. I went down to 110 then 108 then 105lbs. I stayed at 105 for maybe a few months then i started noticing my pants started to fit me loose. So i weighed myself and now i weigh 103.4lbs its like everytime i check the scale it keeps going down. Im not dieting, i eat normally i dont really exercise anymore. So what's going on? I really dont want to drop under 100lbs. When my mom was yonger she lost a ton of weight and she was obsessed with losing weight. The smallest she was was 85lbs (shes also 5ft) and ive seen pictures of her she did not look ok. She was WAY to thin. She now admits she took it way to far when she was younger. But anyways im starting to fear that im going to look like that and not even notice. Im not doing anything to lose weight so whats going on?