Hi Sara,
The doctors will typically check the hormones associated with fertility; FSH (follicular stimulating hormone), Estradiol (estrogen), AMH, LH (Lutenizing Hormone), Progesterone. These tests are done on the blood at certain points during the cycle. Some may even check the thyroid hormone levels since they can affect sex hormones. They may suggest that your husband have a sperm analysis to determine if his sperm have issues w/ count or motility. They will sometimes recommend a procedure called an HSG that will check to see if both of the fallopian tubes are open (i.e. maybe a woman is ovulating, but she has blocked tubes). They may do an ultrasound at certain points of the cycle to determine how the ovaries look and the size of the follicles....
Have you tried using ovulation test strips that show you are having the LH surge that happens right before ovulation? That could help improve your chances since you are timing intercourse properly to meet the egg when it is ovulated by your ovary. Women can have normal periods/cycles, but may not necessarily be ovulating so using the ovulation test (OPKs) can help confirm that ovulation is occuring.
You can go to fertilityfriend.com and it is free to join their basic set-up. It can track cycles, and if you start taking your basal body temperature (BBT) first thing in the morning before getting up using a special BBT thermometer (thermometer goes out to 2 digits, ie 97.82), it can track if you've ovulated (a sustained increase in BBT temperature). It also has a free educational course (sent to your email address) that explains the hormones associated with ovulation and fertility (if you don't know that info already and you're interested). If you sign up for a year ($40), you can also go on their message boards and learn a lot of information from other women experiencing the same issues.
Also, start googling infertility testing online and you will find a lot of information as well. This is kind of long, but the question actually requires long answers (I am not even covering all info here).
Good luck - I hope this helps,
Christina <img src="i/expressions/heart.gif" border="0">