A s far as I am concerned I just look at it as having a really big clitoris, there are a fair few Intersex people who view it the same way from what I have been able to gather.
Also, your skin is your largest organ and is covered in nerve cells, especially in areas like the breasts. Orgasm can be achieved anywhere really, it just takes practice and being self aware. Meditation can help cultivate this.
If your BF hasn't figured out that breasts are fun he really needs a reality check. It sounds like it is time for you to let him know you have needs too, and that he either considers you or you replace him.
Tough choice but it is a matter of self-respect as I see it.
Karen.