Even though 6 month seem like ages when you're TTC it's still within what is considered a normal time. I think that usually a GP wants you to wait 1 year before they will refer you to a specialist unless you have any underlying/pre-existing reasons/conditions.
Have you been charting? If not it might be worth starting - just so that you can establish that you're ovulating and also it will give your GP an idea of your cycles and be usefull in any further investigations.