In my experience, limited though it is, it really doesn't matter so long as the work is good. The first draft of my YA novel (before I knew everything there was to know about word count guidelines - thanks AW!) was way short at 55k, yet I still got requests from my queries. But the ms wasn't working and so I got rejections.
Based on feedback I ended up combining what I had intended to be three books into one big YA tome. Now my word count was technically way over "appropriate" for YA sitting at 120k...but I still got multiple requests for representation.
Through my very long revision process, my agent did suggest we cut down, and I did, but I added too and by the end we're at 130k and it's feeling pretty tight.
Stories come in all shapes, sizes, and lengths you've just got to find the right one for yours. If the work is good I certainly believe it can transcend most guidelines...that said, if your work can fit within the "preferred guidelines" it's one less obstacle and all the easier to get through the agent/publisher door! And it sounds like if you're writing YA that you're in the ballpark right now.
As I understand it for YA, one of the benefits of books being Young Adult is that all the YA goes together - so if you're YA, you're just YA and you probably don't have to worry about classifying it beyond that.
Good luck!