Why is my girlfriend so close-minded about sex?

My girlfriend and I have been dating for over 4 months now and we have only had sex three times and we hardly ever do anything at all sexual. Granted we dont have many opportunities (her parents are always home/she doesn’t feel comfortable doing it at my place(with my parents home)/ or in a car).

She told me she is perfectly fine with going without sex and waiting until moments arise where we have a perfect opportunity (which is hardly ever… literally only one “perfect” opportunity has come up in 4 months). I told her that I respect her not wanting to lower herself to standards she doesn’t feel comfortable with.. and I have told her I wish she was more open to doing it in my car/house but she doesn’t like the idea.

Nothing is changing and it makes me irritated because we hardly ever connect in that way – and it makes me feel more like friends.

What can I do? What can I suggest? How can I handle this in a mature way that won’t make her feel like I am pressuring her or trying to get her to do something – when she doesn’t feel comfortable doing it in these places?