In the astral world you are pure energy. Energy does not need body parts to engage in sex. Therefore, astral sex can be as simple as two energy bodies walking into one another to make one energy body. Don’t let the simplistic nature of this fool you, as the result is explosive and energizing.
If body parts is what you need to use to feel comfortable having astral sex, by all means create a penis or a vagina — breasts. All you have to do by being in astral form is to think of the body part you want and it will form. But don’t be limited – just because in your current life you are female doesn’t mean you cannot create an astral penis – because you can. Reverse for the men, you can create a astral vagina.
The only limitations in the astral world are those self-imposed by you.
If it's possible to make astral travels and engage in astral sex, then it might be a sign that we as spiritual beings in the spiritual world can also make astral sex. Do you believe there's room for sex and erotism in the spiritual world/afterlife?