I've recently started gymming

Hi all, so I've recently joined a gym and about 2 weeks into my new routine (and without any increase in caloric intake) I've gained 1.5kg instead of losing weight. Mind you, I have gone from a period of almost no exercise to visiting the gym 3-5 times a week with my routine typically involving 20 minutes of interval running on the treadmill and 5 minutes high resistance rowing followed by some strength training. With some research I heard the weight gain might be due to the body pulling in water weight to adapt to the increase in physical activity and that slowly the body will retain less water. However after another week I still seem to be stuck 1.5kg heavier than when I started.... I understand that it might still be too early to expect any weight loss but I do feel like I've toned up a bit so it's really quite disheartening to see weight gain.

Has anyone else had this experience? Or can anyone offer some training tips to get faster results?

Thanks for reading this lengthy post hahaha