It could be your cervix, that will have a hole in it. That's the end of your uterus, and can be seen inside the vagina. Some people have a cervix on the right or the left, it's not always at the very end of the vagina. It could also be a sort of normal ridge that all women have, you can feel it with your fingertip if your finger is facing up. I can't remember if that's a bone or muscle, but it's normal. Also, the skin of the vagina is kind of pleated, like the roof of your mouth, don't expect it to be all smooth.
Do you have a gynecologist yet? If not, you might ask your mom to get you one who is female, and book a checkup. When the doc does a pelvic exam she can readily tell you if there is anything unusual about your shape, she will use a speculum to open your vagina enough to actually look. Nobody loves speculums much (ask them to use the smallest one), but if the doctor looked in and didn't see anything unusual, at least you could stop worrying. Also, it's your legal right to have your exam without your mom in the room if you prefer to speak to the doctor privately. You could then simply ask her your questions.