Sparky, I think there are some very important things that you need to consider.
Gender and sex are two different (although related) things. Sex is biological. Male/ female are sexes. Gender is an identity. It exists in the mind and is expressed in many ways. Man/ woman are genders. Trans women were assigned male at birth (an important phrase) but they are still women. Being biologically male has no effect on their gender and, therefore, a trans woman is no less of a woman than a cisgender woman, even if she is not female.
Now, going back to our original disagreement we you claimed that we are gay. I still think that your position is objectively wrong and potentially very hurtful to trans women. Let's consider what people are attracted to when we speak of sexual orientation. I would argue that gender plays a MUCH larger role in sexual orientation than sex does. People are attracted to the group of people they are attracted to because of their entire gender expression, not just their genitalia. Women are not walking vaginas. There are many things that make them women. We are straight for being attracted to women, even if we might be attracted to women who are biologically male. What labels you use to refer to your sexual orientation should reflect the gender you are attracted to, not the sex. Otherwise, you are placing the entire emphasis of your sexual orientation on a persons genitalia, which to be honest, is pretty objectifying.
A very important part of the trans movement is trying to get society to focus on gender more than sex. A person's sex is really their own business. If a woman is a woman in every single way, but she just happens to have a penis, even if you like that penis you are still not gay, because you are attracted to a woman.
Now, I personally define both as heterosexual and queer. I also use the term "trans-attracted" to refer to my sexuality sometimes. I am saying this because I agree that it would be delusional to pretend that there is nothing that separates us from men who date cisgender women. Of course we are different. But we share in that we are both attracted to women so we are all still straight (even if a portion of us are attracted to trans women) . We are more similar to men who date cis women than we are to men who date cis men.
Finally, I want to reiterate a point I made earlier. Your labels are entirely up to you, UNTIL your labels hurt other people. I bet you that 99% of trans women would be very hurt by you calling yourself gay for being with them. In doing so you are saying that they are not women. You are placing more emphasis on their sex than on their gender, even when they are asking you to focus on their gender. So you said that this is your opinion, but opinions can be wrong. Opinions can be hurtful, damaging, and selfish. Yes, we face stigma for dating trans women, but it is nothing in comparison to what trans women face. The least we can do is respect their identities and not misgender them. I am not in denial about trans women's maleness. I simply respect the fact that they are still women. I think you should do the same.
If you are attracted to men or crossdressers (people who dress up as women occasionally but still identify as men) then you can call yourself gay. But you are really hurting people if you call your attraction to trans women homosexuality.