I feel some of the posts are a little unhelpful. Weight can inhibit pregnancy - either too much or too little weight. But it is a marginal factor and I do feel that it is being used to screen out the number of people eligible for expensive help.
It's the same in adoption - factors which have a marginal effect on your ability to be a good parent are being used to screen out possible adopters because there are just too few children for too many parents. So the decider becomes something that would be irrelevant for people who aren't in the queue for adoption (eg, not being married, occasionally smoking, being overweight).
For those who don't really have a problem with fertility (myself included) weight did not stop me conceiving. Simple observation tells you it's a marginal issue not a major factor. Most people who are overweight won't have a problem conceiving. But it's a way to screen the applicants and therefore it has become a major requirement in fertility treatment.
In my case, I was ovulating. If you are ovulating (which you might be with PCOS - I was), clomid won't be much help to you anyway.
I think it does sound like a more sympathetic gp would help to get to the bottom of what exactly your fertility isue is.
I should add that I completely agree with those who posted re BMI being unreliable.
There is a very clear genetic factor in weight issues but it's an unfortunate fact that those who don't know a lot about it prefer to believe that that is not the case.
My mother has suffered from a lifetime of intestinal disease and has a diet of around 1000 calories a day. She is completely consistent in this and I know she doesn't sneak any extra food because she can't. She is averagely active. She weighs 18 stone.