Don't freak out yet. First go see your ob/gyn. He can have blood work done to determine if you are still ovulating. Then, he can draw blood to see if your insulin, thyroid, and progestrone levels are normal. If all of that is okay, he'll want a sperm sample to check sperm count and mobility from your husband. If that's okay, they'll probably want to do an hsg on you, or a test similar. That will tell if you have any blockage, scar tissue, etc. Preventing pregnancy.
So many things can be off in that process above. And, doctors have treatment for each one along the way.
For myself, we had all that done, and the doctors found nothing wrong. But, still not pregnant. We also have one child. We are trying for our second one as well. Been trying for a little over 4 years. I'm now taking a fertility drug. I don't think that'll help though. They are usually used for women who aren't ovulating. Our next option is artificial insemination. (we're gonna give clomid a try for three months first though).
I'll tell you what everyone tells me though. Relax, try not to stress over it. Stress can affect your chances of getting pregnant. I know, easier said than done.
Good luck. But, go see that doctor.