I can't have an orgasm during sex but I can have one orally why is that?

There are two different orgasms, clitoral and vaginal.

When your receiving oral sex my guess is that your having a clitoral orgasm.

Also vaginal orgasms aren't "available" for every woman out there, some are actually unable to have that "type" of orgasm.

You can always try different positions and also stimulate your clitoris whilst having intercourse.

In this case practice is always the benefit.

I have a question:

Do you feel any pleasurable sensations while having intercourse?

Sarah

How old are you?
How long have you been sexually active?
Some women never experience orgasms outside of masturbation.

For women, an orgasm is an emotional connection. You have to be comfortable with your partner, which I would assume you are since you have experience them orally. Relax and enjoy your feelings during sex.