Well, I won't bore you with any useless "teenage bs", but I will share my experience and advice.
I'm 20 years old, have a 25 year old boyfriend of 18 months, and have, at my age, been so fortunate as to achieve the allusive "vaginal orgasm". It's only happened 2 or 3 times for me, and never when I am trying for it. The only common thread was that I was always on top. You could try moving your hips in a vertical circular motion (forward, down, back, up, versus side to side), that's worked for me.
As to the clittoral orgasm... well, your right, there's a good chance it's mental. Have you tried taking care of yourself? That's a nice quick way to find out if it's just you. Otherwise, have you and your boyfriend been fighting, had any serious disagreements lately? Are you 100% comfortable with him? These are all things to take into consideration. My advice would be to try by yourself a couple times to get back in the motion, and stop stressing about it during sex. The more focus and stress you put on the issue, that more difficult it will be for your body to relax and enjoy the ride.
Well, I am going through the same thing right now. I just posted about my situation a few days ago. I cannot reach an orgasm with just sex. I need clitoral stimulation and so does just about 70% of women. Everyone has told me that vibrating bullets and **** rings are the best as they stimulate the clit while you are having intercourse. As far as fantasizing goes, I would really just try to think about your orgasm. Good luck.