Blood Tests

Hi, 
Wonder if anyone can settle my mind at rest... 
I had some initial bloods taken to start process of finding out why we are not pregnant yet. 
I had my tests on day 2 and day 22, as the doctor advised. I received a letter saying I need to book an apt to discuss the results, as day 2 was fine, but 22 was "boarder line" ??
Now I cannot get an apt until 28th December, annoyingly! Anyone had this before and know what might be discussed? What is it they are measuring?