You are definitely homophobic, but in a different way than how people paint homophobics. In its purest form maybe - fear or dislike of homosexuality displaying constitutes your phobia. That you correlates homosexuality with beastiality is definitely a problem.
Disgust induces revulsion, offensiveness, and to a certain degree, aversion and distaste. Those are the very feelings that nourish hate crime, that root it in troubled minds. I do not assert that you will commit one, but your reaction is symptomatical of a social paradigm that entertains repugnance of homosexual relationships. You have to understand that it is in no way a natural, yet acceptable, reaction to same-sex relationship. If you were homosexual yourself, would it be sustainable for you to be disgusted by the thought of a man fucking a woman? You might not be into it, but it does not warrant vomit-inducing reactions. You definitely have a problem that needs to be solved (through experimentation, maybe? ;) )
Btw, anal sex is very popular among heterosexuals as well. I can find you studies about that, and since there are more hetero than gay people in the world, you don't need to be a rocket scientist to figure out that anal sex is most likely performed by hetero people. It is in no way a gay-exclusive practice, and it needs to be dissociated from gay sexual prejudices and dogmas. Anal sex doesn't define us, nor vaginal sex define you. Some perform oral sex, other perform BDSM... Penetration isn't an end in itself.
So yup, you are homophobic. And in order to remedy to that (you wouldn't have posted about it otherwise), you need to question yourself about your preconceptions of what makes something a gay relationship. What is a gay relationship? Bareback sex? Or really just two people of the same gender sharing the same experience as you do with your gf?
It's like saying you're not racist because you have black friends. Sorry, but that does not make you less racist. Agitation, repel, anger, anything that might fuel fear must be wiped off.