To be more graphic, when lesbians have sex, usually when they climax, they're stimulating each other sex organs at the same time, whether it be with hands, or a strap on, or whatever.
They're having ''sex''.
Getting head does not constitute as having "sex".
sex |seks|
noun
1 (chiefly with reference to people) sexual activity, including specifically sexual intercourse
Having head is not intercourse.
The male anus has glands which are stimulated during arousal, leading to a "happy ending" - like the female equivalent, the vagina.
Putting your schlong in someones mouth is only stimulating one person, therefore, I don't think it could be classified as having sex.
Either way OP, if you love having sex with girls, yet don't love having sex with guys (you've ruled out anal) - haven't you pretty much answered your own question?