Am not losing weight .. what?

hi , am 18 yrs old... and myself losed weight from 95kgs to 75 kgs ....now am 75 and still wanna lose weight... but the fact is am not losing weight but getting thinner than i was actually... but the weight remains the same for past 2 yrs ... neither increased or decreased... is it my muscle weight or fat.. i do lots of cardio exercieses.. please help me with this ... thank you ...