hi, you say there is nothing obviously wrong, but if you have been trying for over two years and still nothing, it might be time for more detailed investigations a a fertility clinic, if thats the way you want to go. you might need your tubes unblocked, or medication to help.
As an aside you might also want to start saving up for private treatment because if it's anything like where i live, if you needed, say, IVF, you cant get it on the NHS till you are 30.
I also agree with the others about relaxing. After 9 years of trying, i finally came round to the idea i'd never be a mum and lo and behold i am now about 9 weeks pregnant