Loosing Weight While Weight Training

Hey ladies, so I’m back at the gym after over a year. To begin, I am about 5’3 and weight 101 lbs. I’ve been weight training with the help of my boyfriend for about 4 days for almost 1.5 to 2 hours per day. Before going back to the gym, I’ve always eaten a very clean diet. I’ve recognized after working out, I can see my muscles more and I’m not bloated at all. However, it appears that I’m possibly loosing weight? First time I went to the gym I weighted 101.6, two days later, 101.8 and two days ago 100.4. Not sure if I should be concerned. I looked healthy, but I can tell I’ve lost weight. Any advice would help. Thank you! *Additionally, I’m trying to increase my weight gain and eat things high in calories like nuts, lots of olive oil, carbs, etc.