She wants you to stop. Maybe you have to make a point of not going that far. If she actually desires you, and her hangups aren't too severe, then by holding back a little will probably cause her to want it more, and eventually you can get past whatever the barrier is.
That said, respecting boundaries is one thing, but it sounds like you've been dating someone for *six months* with the expectation of sex (quite reasonable), and it just hasn't happened. She's not being fair to you. If you aren't both consciously waiting for some future date, and she isn't ready, you need to understand that she's had way, way, way more time than most people need to get comfortable with another person, to say nothing of the 15 or so years she had before meeting you.
Unfortunately, as a very late bloomer, I'm speaking from experience: having waited this long yourself, you have an uphill battle in front of you. It takes a while to get over the anxiety surrounding sex, and then you have to spend time getting good at it. On the surface it seems like someone who's going through the same things as you is a valuable find because you can get through it together. But it's also possible that throwing another person into the mix who, for one reason another, managed to make it to late adulthood without having sex, is going to further complicate everything.
There are many women out there who will like you for you, and the good ones, when you tell them you are inexperienced, will say, "then let's fix that."