First off, you aren't doing anything "wrong." The sad truth is it is harder for women to orgasm than for men, as it isn't biologically required.
19 is no age really not to have orgasmed, a lot of women in their 30's tend to experience it for the first time. There is nobody here who can say "this is how you do it," everyone is different.
However, there are a few general pointers. The first is possibly the most important. Don't worry. Don't try and achieve an orgasm, dont sweat it if you don't cum. Enjoy the journey every step of the way whether you do or don't. Stressing about whether you can or not is about the surest way not to.
You need to be relaxed (for a given value of relaxed), and turned on mentally and physically. Doctors say that the majority of women wont cum purely from penetrative sex, so be sure to pay attention to your clitty.
Another thing is that your clit is bigger than you suppose. Like an iceberg, you only see the very tip. Stroke around the outsides of the clit, press down towards your labia, there is a large area of sensitivity there. Find a place that feels good, experiment, direct clitoral stimulation can be too overwhelming. A good excuse to explore yourself, stroke your whole pussy, find out where the sweet spots are.
There is nothing stopping you cumming, but so long as you are enjoying yourself, and it sure as hell sounds like you are, then more power to you. HAVE FUN and dont sweat it, it will hit you one of these days.
