Given the fact that you are trying to conceive for one year now, you might consider testing your fertility. There are many factors that might contribute to infertility. Both the physical condition of the genital tract and the chemical balance maintained primarily by the hormones are important.


You might want to visit your gynecologist for a physical examination. An ultrasound scan might reveal any physical problems with the ovaries and the uterus. Cysts might be found on the ovaries and fibroids in the uterus, for example. The hormonal blood tests might reveal the presence of a hormonal imbalance which might need further hormonal therapy in order to restore the regular hormonal production. The hormonal production of other glands (pituitary gland and thyroid gland) might affect the hormonal production in the ovaries as well.


Immunological problems might be present if antibodies against the semen are formed. The acidity in the vaginal environment have to be at a specific point for the spermatozoids to survive.


In the end, there might be a bacterial infection present. For example, presence of infection with Chlamydia might affect the chances for conceiving and the treatment is quite simple (taking antibiotics for some time).
Visiting your gynecologist for tests for pregnancy might help you not to waste your precious time.


Also, in the “list of other diseases” you mentioned colon cancer which was removed. Depending on the treatment afterwards (radiotherapy or chemotherapy), you might need to consult with an oncologist to check if the treatment might have somehow affected your fertility.