Hi Wonky, I agree with everyone else here that you should try a more supportive GP. Also, I don't know if your husband has been tested, but if not, the problem may not be on your end. Some friends of mine tried and tried, and eventually the man got tested. Turned out that he had low sperm motility, which was fixed with a simple procedure. A few months later, his wife was pregnant.
Good luck; maybe you'll feel a little more hopeful with a different GP who has a different approach. If nothing works, go ahead and splurge on the chlomed!