opposite sex

Assalamu alaikum wa rahmutAllah, this matter I am about to ask you about has been a nagging issue in my mind. InshaAllah I hope you are able to provide me with a response to the best of your abilities. I am a 17 year old female public high school student. I have been in companies of all sorts, from the mixed genders of non-muslims to those of the same sex and same religion, but very much astray from the true light of Islam. It was not until a year ago that I became friends with a muslim boy who is very involved in the MSA and has introduced me to his muslim friends whom are all firm believers and good followers of Islam. The problem is, all the girls in my school that are muslims do not concern themselves with the deen and unfortunately are even comparable to the lost non-muslims who do not think of matters other than boys, sex and looks. I've always attempted to steer away and have not found salvation until I became friends with this boy. We always discuss Islamic matters to the best of our abilities and we always give each other good advice. This has allowed our friendship to grow but we steer away from haraam matters at all costs. I am usually found sitting in the library with this group of muslim boys. We do not chat about useless topics, rather we discuss many relevant matters to Islam and our studies. Is it permissable for me to say that my best friend is a boy? How can I approach this "gender dilemma" more Islamically? JazakAllahu khair. (P.S. as in, what are my boundries, limits, etc)