Hi. I'm so sorry to hear of your losses.
My first thought is that you need a better doctor. This guy doesn't sound like he knows what he's talking about or simply not explaining it correctly. I'm confused.
Like coppertop said, you wouldn't be pregnant if you're not ovulating. And not everyone ovulates every month, but what does that have to do with m/c's? There are multiple reasons why maybe the pregnancy isn't 'sticking', could be a blighted ovum, checking the health of your eggs, or it could be low progesterone etc...
Also, you could have something I found out I have. There are many women now who've found out they have it after having had several m/c's...a blood clotting disorder. I had a couple superficial blood clots in my 20's due to the birth control pill. When we conceived this December I didn't even think about it. My mom immediately reminded me and when I told my OB/gyn she gave me a special genetic test. It came back that I have a genetic tendency to blood clots. Had to start giving myself two shots a day of blood thinner so that I wouldn't get a clot or that there wouldn't be one to the placenta (thus m/c). This is more common than we ever knew before.
Please, find a doctor that will do whatever is necessary to discover why you've had several m/c's and help you find a solution. You deserve to have a happy healthy baby! I know I can't imagine how you must be feeling right now, but please know our thoughts and prayers are with you.
In love and light, L & J (baby EDD 9/15/03)