Yes you are totally right, guro is erotic gore, but it is not that easy to tell which is which because any gore cat be erotic depending on context.
It is not necessary to focus on genitals and lots of guro is not related to genitals at all. probably it could be even said that guro is not as much about gore as it is about absurdity.
However word fetish is also by definition sexually related, so if you are "asexual" you cannot have any fetishes. or you are not asexual after all.
Guro is grotesque*
I think it's more about what it is better known for, rather what it really means. Gore MEANS graphic and bloody violence, but the term is often used for "live-action" or real life scenes depicting any sort of death or serious injury. Guro MEANS "grotesque" and originally was referred as "Ero-guro" or "erotically grotesque". In the beginning guro only was about pretty weird and disgusting fetishes (mostly in manga or anime). Nowadays is more known for deaths and blood even without sex or eroticism involved. But guro still is better known as the anime counterpart of gore.
What do I enjoy the most? Gore is sometimes pretty exciting to me as long it's not real life shit (like those rekt, accidents or executions videos). When it comes to guro on the other hand, I like pretty much everything about it (except for furry and yaoi stuff).