Hi Lauralee,
I am SO SORRY you are going through this. Sometimes there are just no answers for why a couple can't get pregnant. Have you considered adoption? Let me tell you a story that may give you hope. My cousin and his wife tried for like 4 years to become pregnant and nothing. They had test after test after test and they thought there was a problem with his penis (try not to laugh cuz the way I put that is kind funny) It was something with his veins in it or something...he tried to explain it to me but being his first cousin I was a little uncomfortable talking about his penis with him. So they thought they had fixed it but still nothing. They even did IVF and nothing. They chalked it up to her going into early menopause at the ripe young age of 33. They also didn't think the quality of her eggs were very good to be able to sustain a pregnancy. They were devastated.
So they started the adoption process and after about a year and a half they went over to China to get their daughter. During the two weeks in China Jen was not feeling well (I'm sure you can figure out where this is heading) and a day after they got back from China she went to the doctor and they told her she was pregnant. They had a 2% chance of ever conceiving on their own!!! Well they now have a beautiful healthy baby boy. They basically just took the pressure off and BAM it happened. They decided against doing IVF again cuz she had a horrible time with all the meds she had to take...just had intense reactions to all of them.
It's weird how some couples have no trouble getting pregnant and others just can't. I was told as a teen I would probably have trouble getting pregnant d/t weird screwed up cycles and not ovulating. Well I proved him wrong. Our first daughter was conceived ON THE PILL (she's five now). Our second daughter was conceived using 50 mg of Clomid on the very first month of trying (she's 3 now) We plan to start ttc our 3rd this August using 50 mg Clomid again.
Here is my advice to you. Are you absolutely positive you are having sex at the right times in your cycles? Do you chart? Temp? Since temping and charting are worthless for me to do d/t not even getting a period unless I'm on birth control pills here is what I suggest. Have you ever heard of Clear Plan easy fertility monitors?? This device is totally amazing and so unbelievably accurate. I like them better than ovulation predictor kits cuz it gives you the days up to AND including ovulation vs the kits where often times by the time you've tested you've already ovulated. It's best to catch the egg when it's high up on the fallopian tube and young instead of catching it towards the bottom of tube where it's aged as there is more of a chance of miscarriage. With the fertility monitor you pee on a stick and insert it into the machine and it reads your fertility and tells you when to have sex. The monitors are kind of expensive (mine was $175) and sticks are 30 to a pack but worth every penny in my opinion. You could even check Ebay or Craig's list for one.
I hope this helps. Feel free to write if you have more questions. I've heard often that's it's when you aren't "trying" that pregnancy happens. Just try to go about your life and not make making a baby the only thing on your mind and maybe it will happen. Again, I'm so sorry you are going through this. But maybe some of this advice will help.

Kara

PS If you do get a fertility monitor post me and I'll tell you exactly how to use it ok? I'm a pro with mine