Honestly? It's probably nerves.
You'd probably be feeling that way whether your sex was protected or not. The funny thing about wanting to be pregnant, suddenly every little thing you feel makes you wonder, "is this it?" it sounds silly, but you could sneeze and your brain will think "aha! I must be pregnant!"
i think it's a bit early to be feeling anything just yet. I don't think a fertilized egg would even be implanting yet.
But keep us posted!