Dear Shelly,
Depo provera works by thinning the endometrium, thickening the cervical mucus and inhibiting the hormones that stimulate the ovulation. The side effects are numerous. They can be nausea, fatigue, abdominal discomfort, sore breasts, depression, weight gain and significant loss of bone density. Due to this the FDA suggests that it not be used for long term birth control. Women experience menstrual irregularities for 3-10 months after use and only 68% conceive within 12 months, 83% within 15 months, and 93% within 18 months. Whether it was used once or a long period of time does not seem to matter. So even if you are ovulating the quality of the cervical mucus (necessary for sperm survival and movement to the egg) or the endometrium may not be optimal.
The best I can suggest is to be patient (anxiety can also be a cause of temporary infertility) and monitor the cervical mucus according to the Billings Ovulation Method (BOM). Try to conceive when the quality of the mucus is best, that is, near the last day of a slippery sensation that has been preceded by several days of changing mucus. The mucus has progressed from damp, sticky to stretchy, slippery due to the increasing estrogen produced by the follicle as it matures toward ovulation. After ovulation the egg is available for fertilization 12 to 24 hours. Progesterone is then produced and has a drying effect on the mucus.
To help you start making correct observations you should contact a Billing Ovulation Method teacher for instruction. Because the knowledge can be used for achieving or avoiding pregnancy this will be helpful now, and for the rest of your reproductive life!
Angie Frausto