I’ve always loved my close friends deeply, but rarely desire sex. I know there are polyamorous asexuals, but could I call myself “polyromantic” and still have myself be understood, if that’s the term I prefer to use?

You can identify in whatever way makes the most sense to you! When it comes to making sure other people understand, there’s no linguistic silver bullet - you may need to explain and clarify what you mean, and people may still have misconceptions or questions. That’s part of the territory sometimes. Once you’ve had the conversation a few times, you get pretty good at anticipating questions, explaining things in broad strokes, and knowing when to avoid the topic if you don’t have the energy to give someone an education. 

Remember that in the online world of tumblr and forums and sexuality blogs, there are hundreds of little distinctions drawn between the many identifiers people have developed - you’ll find people identifying as “gray asexual,” “aromantic,” “polyromantic,” “polyamorous asexual,” etc. and you’ll find other people arguing over what those words really mean, and who gets to use them, and drawing even finer distinctions. But offline, the vast majority of the population hasn’t been exposed to this discourse, so it’s less a matter of finding the exact right vocabulary to describe yourself, and more about learning who you are, living into your true self, and knowing your boundaries when it comes to having the “coming out” conversation with various people.