I'm going back a while now, but we went to the doctors because we weren't falling pregnant after I had a miscarriage.
I had the CD21 blood test and the CD2-5 blood test (the FSH one that checks the quantity - and quality maybe(?) - of your eggs). Mine came back fine. My husband had a sperm analysis, which came back slightly lower than they'd like to see, I think it was 18 million. So his count was on the lower side, but I think most of the other factors relating to sperm were ok.
So I then had to go through other testing. They did an internal ultrasound to check my ovaries, which looked fine. They did an HSG, which is dye through your tubes to check for blockages. That was fine. I had a lap and dye to check things a bit more closely, that was fine.
So basically the specialist told us that although my husband's count wasn't the best, I should be able to get pregnant, but obviously I wasn't so she put us on the waiting list for IVF. I think I was on that for over a year when I got the call to go in to get the ball rolling. By this point though, I was 6 weeks pregnant with my now 6 year old. I desperately wanted to have at least 2 children, so didn't go back on the pill after having him, and conceived first cycle with my now 5 year old.
I think my eldest son was born 4 years almost exactly after we started trying. It was a long, long wait, but all I want to say is even though you may get referred for IVF, don't give up hope of it happening naturally for you. Good luck x