Bmi too high to conceive?

Myself and my husband have been TTC for 20 months now and recently got an appointment with the fertility clinic. My husband has been checked and he is fine. The first thing the woman said was that my bmi was too high. It's currently 38 and she wants me to have a bmi of 33 by 6 months for our next appointment. I am fit and healthy and exercise 4-5 times a week for at least an hour I eat healthily too apart from the odd weekend. My periods are regular each month and always on time but it seems I'm not ovulating. Does anyone have any advice or am I just gonna have to loose the weight to get help from the NHS