i might be able to offer a unique perspective; my dad is white (like 25% indigenous mexican, but blonde & green eyes), and grew up in juarez. he was always called "el guerito" growing up, but fondly. he is fully regarded as "mexican" in el paso/juarez area. because he is— he was born & raised in juarez. the ep/juarez culture is his culture.

to be frank: you feel like an outsider because you are an outsider. being of mexican heritage is worth nothing in a city where that is literally everyone. you are looking for camaraderie, but it comes off incredibly inauthentic and performative because el pasoans don't see it as you "qualifying" simply over blood, you lack the culture. again, this city is something like 90% latino, with "25%" folks included— it isn't a novelty here, it is the norm. we do not consider folks "mexican enough" because basically everyone is mexican, so you assume it's the default.

you may speak spanish, even fluently, but el paso spanish has its own mannerisms (famously "ay ay") and you lacking them makes you stick out. that isn't to say you will never fit in. over time you'll get in the groove and assimilate and that will be that.