If you are under the influence so much that you are not consenting (and not realizing that you are having sex is really under the influence), then YES, this is RAPE!!! It doesn't matter the age! If you are so high or drunk that you cannot consent, then it is rape, even if you are both 25. (I'm not judging you about being under the influence...just saying that there's a difference between a buzz and being drunk).
If this happened to you, you need to tell someone about it. Your parents, your school counselor, or even call the RAINN hotline, at 1-800-656-HOPE.
I hope that if this happened to you, that you are ok, and that you'll get the help you need. Good luck!