You sound like a very supportive mom who loves her son. So don't feel bad about not understanding his orientation. I'm a girl who likes girls. No Ive never been with a girl or guy, but I still have feelings for women. I don't have to experiment to know I like girls because I just do. I believe pansexuals are attracted to anyone, regardless of sex or gender identity. When he is ready, he'll talk to you more about it because like I said before you sound like a really loving and supportive mom, so I'm sure he'll come to you and talk about this with you.