I wouldn't worry yet, especially since this is your first. I bet when you DO feel those flutters, you'll be surprised that you can recall feeling "something" for a while but just didn't recognize it! That's how I was with DS. I wasn't sure I felt movement until I was actually at the 20 week ultrasound (at 18 1/2 weeks then) and saw him kicking and squirming...then I realized what I'd been feeling all along was him.
I'm 16 weeks and I'm noticing movement now, but it is faint and hard to recognize yet. It's kind of like I'll realize I've felt something, and then again, I'm not 100% sure I did because it's so quiet and faint and gentle.