Female self-pleasuring methods

I'm a 15 year old girl, who is also a virgin. I have also never been touched "down there" by a guy before(I'm straight). I've been masturbating for maybe a year or so, and I've never had an orgasm. I really want to though. One of my friends who has had a lot of experience in the sexual arousal world has said that it is one of the best feelings ever. I know how it's done and everything, but I just can't seem to have an orgasm, no matter what I do. I've watched porn, used a toy, fingered, and just about everything. I have read that if it feels like you have to pee, it's probably your body getting ready to squirt. I've never done that before, but I get that sensation a lot. Nothing ever happens with it though. I get very aroused and everything, but nothing ever happens...why is that? Is there anything I can do to give myself a better chance of having an orgasm?