What can I do to tell if I am fertile?

Fertility. See a fertility specialist to have testing done to determine if your sperm or eggs (man or woman) are in good working condition.
Fertile? Many factors determine fertility but the woman's egg quality is the most important (yes, open tubes and sperm matter a lot too). We can use blood (amh & fsh) and ultrasound (antral follicle count) to get a reasonable guess at egg quality. We use these tests for women who want to delay for career or who are having cancer treatment. See gyn or fertility specialist for details. Best wishes.
Assess your history. If you have regukar periods..It is telling you you ovulate every month if you have folliwng risk factors...Then you seek evaluation: 1. Irregular cycles- <25 >42 days 2. Abnormal-excessive hair growth 3. Breast discharge 4. History of pelvic infections-pelvic surgery 5. Exposure to chemotherpay 6. >35 years of age.