Need advice on my cardo/weight regiment?!

Need advice on my cardo/weight regiment?

ok since its been summer i been going to the gym a lot more, from 3-4 to 6 times a week. im 5'6 and 21 years old, i watch what i eat very well and my mom helps because my dad and bro have blood pressure problems so im covered there, in the four days i do weight machines and of course i do different parts of the body every day, i do 45 mins of cardio on the eliptical every time im at the gym and its the first thing i do. i get a good sweat and a good heart rate where im not dying or taking it easy. the thing is my weight is fluctuating between 168-172; i have lost weight phsyically but the scale is tripping me out. im concerned as that my muscles are filling in whatever weight i lost? also in my family the men can't really get buff or huge muscle but we can get toned, so even though my muscles aren't getting larger are they still gaining weight?

you are not losing weight because the fat from your body is replaced by muscles. But im not sure why you are still gaining weight even though your muscles doesnt seem to get bigger. Maybe it is all the water you take during your workout.