Wow. 24 yrs, and met at 19 nonetheless. Congratulations! And Happy Anniversary to you both! :3
To be honest, I once asked someone how they knew that their partner was the one. (Mind you, I've had my share of relationships then, but at the time I was single, and wondering if the guy I had my eye on was the ONE) They answered me very simply, that when you find him/her, you just know. It's not something one can really explain in words, but is such an experience that you cannot miss, fake, mistake for something else, or even deny.
When they told me that, of course I was left wondering at such an answer. I mean, it seemed so vague.
About two years later or roughly that, it was then that I finally understood what they really meant by it, because I finally got to experience it. The way your husband explains it is a close explanation, but I'm sure even both of you would agree that it's even more than that, there are just things that are so hard to word. :3
I know this answer doesn't exactly clearly explain romantic love to someone who's never experienced it, but this is the answer I will always remember, and the answer I will continue to pass on to those who ask me. :3