I share the same feelings with your boyfriend of being done too fast... the more you have sex, the longer he'll last, and the more you'll enjoy it... there is nothing wrong with masturbation, or any position. My girlfriend shares the same feelings with you. I have talked to several women, and many of them do masturbate... it normally takes some time to get that out of them because they are ashamed of it... the truth is that there is nothing to be ashamed of, it's perfectly natural... exploring yourself is the best way to know what you want/need. I actually researched via porn how to preform cunniligous on my girlfriend, and that works great for warming her up, so if you can get your b/f to do that, then have sex you should be golden :)