You do sound very mature.
You are also dealing with the issue of losing your virginity here - not an easy one.
But you must understand that taking a friendship to a sexual level puts a lot of stress on things. If you have a fall out, or one of you decides it is no longer for you, the chemistry between the two of you may prevent any sort of friendship to exist. I've been there - I was 23, and my GF was 39 - the first time I'd been with a woman. Started out as an amazing friendship, drinking wine together in the evenings. Then one night we went to a club, which was mainly for gays, and got dared to kiss. That's where it started. And it was an amazing intense relationship - I loved her with all my heart. But it wasn't to be. It took nearly a whole year of not seeing each other, hardly e-mailing or smsing... for the chemistry to die down and only now can we be friends without getting turned at the first sight of the other party. Make sure you are prepared to risk the friendship - it's a fair risk, as the rewards can be awesome!

Sex between woman tends to be (in my opinion) very emotional