Get some calipers (pretty cheap, can be found for $10-15), and chart body fat % along with your weight. That way you’ll know if a drop of 5 lbs. in body weight is fat.
For example: you weight 200 lbs. with 20% b.f. Your body composition would be (200 x .20) = 40 lbs. of fat, (200-40) = 160 lbs. lean body mass (obviously not just muscle as this includes your skeletal structure, organs, etc). Then you drop 10 lbs., leading to a drop of b.f. to 17%. Your new body composition would be (190 x .17) = 32 lbs. of fat, (190 - 32) = 158 lbs. of lean body mass…meaning a loss of 8 lbs. of fat with a corresponding loss of 2 lbs. of lean body mass.
One final note: different diets lead to very different results when losing weight. If you drastically drop calories while increasing cardio you’ll probably find a huge loss in weight, but a good deal of that would be muscle. However, putting yourself in a slight caloric deficit (meaning you burn more calories than you consume over the course of a day), then slowly decreasing calories from there, would lead to slower fat loss but would also help in keeping your muscle mass intact.
Hope this helps!