Hi Bloomingnora - just wanted to offer a few words of encouragement. Going to the docs is not admitting that there is something wrong, it's showing a willingness to find out whether or not there is something wrong, and then facing up to it if there is.
As some of the others have said, there seems to be an incredible incidence of people falling pregnant just after they have started tests.
As you've fallen pregnant before then the chances are that there isn't anything seriously wrong. I try to think of ttc as a bit like rolling a dice - even if you do everything right each month, there's only about a 1 in 6 chance of falling pregnant. Some women will throw a 6 every time, and others will be rolling 1-5 for many throws before their lucky 6 comes up!
I myself spent over 3 years ttc before conceiving the first time, then lost that baby and went on to spend another 7 months before conceiving again (am due in Feb). Allow yourself a couple of days to wallow when AF arrives, and then try and think positively that this will be your month!
Have you tried cutting out caffeine, alcohol and processed foods? I really believe (as does Zita West) that these make an impact.
Hoping it happens for you soon.