You should see an infertility
specialist if you are unable to conceive after trying continuously for at least 6 months. The array of investigations starting from a complete checkup of the couple include sonogram, blood tests, tests for ovulation and tubal patency, semen analysis
and exclusion of other male factors. The management depends on the cause diagnosed. I advice you to see your doctor first for confirmation of pregnancy
or otherwise as your pregnancy tests
are negative. Good luck.